Back in Fischer's day wasn't it of the opinion that a rating like what Carlsen has now was unachievable?
Yes, and Fischer didn't acheive it....
I don't think the case is being made that no-one will ever reach 3000 -- ratings inflation effectively guarantees it will happen, but it very likely won't be a player from this generation.
Next 5 decades, for sure (it took 40-ish years for the the ratings of the bulk of "strong" GMs to inflate from the 2600s to the 2700s)...next decade? No way, not unless FIDE changes something about the ratings system.
40 years after Fischer retired the World Champion had the same rating as him. Rating inflation isn't so huge that 3000 will be possible in a very long time. If Fischer had continued playing he would have dropped from his close to 2800 rating. He lost rating points by going +5 in rated games in the match against Spassky. He could even have won a match against Karpov 10-0 and still lost rating points if there just hadn't been too few draws. It just wasn't possible to stay that high in those days, just like it isn't possible to get anywhere close to 3000 nowadays.
Well, probably none of patzers won't be rated that, their level of playing will be pretty same.
I'm guessing he'll peak at 2931.
Carlsen is nearly 2900.
he is already 2890 so it looks very possible!
+5 in next 8 games to get over 2900...
How does one go about finding our their own ELO rating?
i think its possible if he keep this incredible shape,he just doesnt lose games anymore and pull wins out of nothing. we will see how long it lasts
Carlsen is just a god. Really amazing, that he has such a reputation, and he can still live up to it.
I think Magnus does not like to play engines mostly bcoz fear of getting demolished every time... So until he changes his attitude he can't reach 3000. Coz the engines are only path leading to heaven, I mean above 3000... But until now no sign from Magnus to rely on engines to fulfill ur wishes all u patzers...
Engines are not Fide Rated.
Even if he out performs in a match against an engine, he wouldn´t get any rating points.
Breaking 2900 is of course possible. Breaking 3000 is only possible in a mathematician's dream. Practically, there's just no way that will happen (as long as we are talking about FIDE ratings).
after beating Anand 10 straight games, 3000 should be extremely possible.
Breaking 2900 is not only possible, it is going to happen. Carlsen will become the first Master to reach that milestone. Reaching 3000? Don't hold your breath...he has too much of a distance between himself and the field for him to reach that cloud. The perfect storm would need to happen for him to do so...a greater number of players above 2800, and then he would need to beat them like a drum. 
Even beating Anand 30 games in a row wouldn't be enough to reach 3000.
He wouldn't need more people over 2800; he would merely need to beat 2700s more consistently for example. A 300 point gap would mean he would need to score about 90% vs 2700s; that's asking too much I think.
2900 = Magnus
3000 = Seeing that Bh8 trick at 2013 candidates Carlsen vs Svidler Match. which is nearly nearly impossible. C'mon nobody can play chess at that level. I think 2900 should satisfy Carlsen when he gets there 
No one is disputing that it was unachievable back then. I'm simply saying, in a round about way, that if 2800 was unthinkable in those days, what is to say that 3000 isn't possible in the next decade, or in the next 5 decades?