Yuri Shabanov became a GM at age 66.
True, but a lot of super strong Russians got the GM title very late in life as they hadn't previously been allowed to play outside the Soviet Union and get title norms and so on. They were generally very strong in their youth also.
But yes you can improve, or at least, discover new things about the game and enjoy it. Why not? 
Shabanov hit his all time peak rating in 2001 at age 64.
Vassily Smyslov was playing at Elo 2610 at age 63 pretty close to his all time Elo peak of 2620.
In 2015 my rating was 1458, today its 1255, if anyone can explain this deterioration in form I would be most interested, and no I have not got dementia, lol, my age is 63
Cheers mate, now I'm getting worried, nope I just won a great game against a higher rated player so nothing wrong with my brain
....my guess is you'll probably deprove. But that's okay. You're playing grandpatzer chess & that's pretty good. Feel satisfied 
!
....my guess is you'll probably deprove. But that's okay. You're playing grandpatzer chess & that's pretty good. Feel satisfied !
lol....might be grandfatherpatzer chess some day....if my shy son gets off his butt.....one can only hope.
In 2015 my rating was 1458, today its 1255, if anyone can explain this deterioration in form I would be most interested, and no I have not got dementia, lol, my age is 63
Doesn't sound too bad. If you're a 1350 player you'll probably see swings of 100 points either way. You'll probably soon go back up 100 or so points without really doing anything special; it would just be regression to the mean.
You can always keep on improving. I know a bunch of 70+ year olds that have gained over 200 USCF rating points within a year. Just put your mind to the game and persevere.
In 2015 my rating was 1458, today its 1255, if anyone can explain this deterioration in form I would be most interested, and no I have not got dementia, lol, my age is 63
Three possibilities come to mind. In increasing order of possibility, they are:
1. Your game may have actually deteriorated.
2. Chess.com has changed the formula (I see many 2000 rated players of 2015 are now around 1800).
3. You played more tournaments in 2015 than now. In tournaments you get a lot of free points as 30% games are lost on time. So if we complete a tournament without losing on time, usually our rating goes up. Great for ego but nothing in substance really.
Many players here are using chess engine, especially in online chess games. I hate cheaters.
In 2015 my rating was 1458, today its 1255, if anyone can explain this deterioration in form I would be most interested, and no I have not got dementia, lol, my age is 63
Three possibilities come to mind. In increasing order of possibility, they are:
1. Your game may have actually deteriorated.
2. Chess.com has changed the formula (I see many 2000 rated players of 2015 are now around 1800).
3. You played more tournaments in 2015 than now. In tournaments you get a lot of free points as 30% games are lost on time. So if we complete a tournament without losing on time, usually our rating goes up. Great for ego but nothing in substance really.
I actually think that over time it has gotten harder to be high rated...I knew several players that played back in the 1970s through 1990s and they claim they play just like always, but the competition got a lot better over time and their ratings have dropped 200-300 points. Also at the club I used to run when I was only about 1500ish, I had several players drop in that said they used to be 2000ish like 10 years ago and they were really easy to beat repeatedly, but they may have been rusty or exaggerating. I always thought that chess was like riding a bicycle though.....
In days when I was a regular cyclist, I would put left foot on left paddle and as the bike moved a little forward, bring my right leg round the seat and would be properly seated in one seamless motion. When I tried the same after about 20 years, I found to my disappointment that my right leg won't go round the seat - I could not lift it high enough. So I fully sat on the seat first and then cycled on. From there on I could balance almost like the old days...almost, not actually. While getting off the bike, again it was not like the olden days. I had to bring the cycle to full stop and then only I managed to get off.
So yes chess is like cycling. If you play after a long time you openings and endgame will not be as good as in past and middle game will be rusty too. But you will manage and if are careful, will not embarrass yourself and your dear ones who thought you were as good now as you were in your youth.
....Are you "sufficently bad?" I don't know. Maybe not. I distrust a lot of "you can improve at any age!" stuff, because obviously that's not true. It just depends on the person. So the obvious, and not very useful answer is:
Improvement is neither impossible nor is it guaranteed.
I LOVE this response and it really has the mark of truth. we have a Major issue with swagger in the forums- How can you really Answer what is asked in the title?you can say people have gone up on rating in their 60s.... but then people have lost their minds too; or died , so clearly failure & frustration are possible as well
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in the end, the whole question is unanswerable and probably an unhelpful question to even ask. if you want to improve- giving yourself this great doubt will certainly sabotage what could have happened. and furthermore; it will always be easier to sabotage your program and blame your age.
OTOH, a bold confident effort will always be better with no hesitations and total commitment even if it fails. and its hardly unprecedented to see people improve, at any age. so you might as well as go with the happy emoji troll queen and
say "You can always improve!!! 
"
OR not.
give up on it and spare yourself the emotional investment.
Depends on what you mean by "Improve."
If you wanted to say, can I be better than I was yesterday, or the week before? Then sure, it's trivial to affirm that you can improve at the age of 63.
If what you meant by "improve" is the following: "Can I improve at the age of 63 to attain a higher official USCF classical rating than I have ever before done, to set my personal record and my personal best, then that might be a little harder, or in some cases, impossible."
Take for example, Garry Kasparov or Yasser Seirawan or Jeremy Silman. Are these guys going to *improve* at their current age so much that they will surpass their previous heights in 2 years?
I would bet big money that they won't. But if your goal is to get better than what you are now, then sure, absolutely, you can improve at age 63.
Repost:
"Yuri Shabanov hit his all time peak rating in 2001 at age 64.
Vassily Smyslov was playing at Elo 2610 at age 63 pretty close to his all time Elo peak of 2620."
I want to hear more opinions from 15 year olds how being over 60 doesn't mean anything, you can always improve at everything, and your body and brain definitely don't decline at all... lol.
I found that my memory has definitely gotten a lot worse, but most other mental functions are about the same, as far as I can tell??? (if you start losing it I have noticed that many people can not seem to tell themselves), so maybe I can at least not "deprove", seem to be holding steady for now. Sorry to ask the proverbial unanswerable forum question, but how many of the questions here can be answered with 100% certainty, not many that I have seen.
It's altogether different for us sub 2200 players or sub 2000 players to improve as compared to Grandmasters who hit 63.
63 year-old GM have long passed their ELO peak. They know they'll never reach their personal bests anymore.
Yuri Shabanov became a GM at age 67.