I'd choose Caruana as the most likely. I'd like to see Nakamura but he is too inconsistent. The days of a Tal style world champion are over.
Who will be Carlsen's next (or rather first) Challenger?

Simply Kramnik. Believe it or not, he's only 15pts away from his peak. I suspect Kramnik's next challenger would be French Maxim Lagvier (?? Sorry, completely forgot what is his name..)
EDIT: This one! http://en.wikipedia.org/wiki/Vachier-lagrave ;)

Kramnik came very close to winning the right to challenge Anand. Carlsen only advanced on tie-breaks. Good call.

I think Kramnik would make a good candidate as he is certainly capable of giving Magnus a good run for his money. IMHO oll other contenders are a class below Carlsen.
Caruana, Nakamura and Gelfand can never play in the next title match since they didn't qualify for the Candidates tournament that is held in March.

Kramnik would be the best challenger in a WC match of the candidates that will be eligible, but apart from that, of the people listed I would bet on Caruana joining the 2800 club permanently and becoming the one most capable of challenging Carlsen.
Although Kramnik is also reaching the age when he could start declining seriously in the next year and not be at his best, so perhaps he wouldn't be a good choice.

I Think Kramnik Will be, but as Kasparov Said is it the match Aronian- Carlsen we all are waiting for.

People were talking about looking forward to watching Carlsen-Kramnik, before the last Candidates tournament even finished.
Carlsen-Ivanchuk could certainly be an exciting match, though, given the daily lottery of which Chucky shows up to the board (to be clear, yes, I know Ivanchuk isn't in next year's candidates, but he might be another year).

Kramnik and Aronian certainly have the highest probability of being the next challenger. But Topalov is in great form recently. He may be someone to be reckoned with.
And may I remind some of you that Caruana, Nakamura, Ivanchuk and many others are not possible, because they do not participate in the next candidates tournament.

I can tell you now that it won't be Caruana
http://en.wikipedia.org/wiki/World_Chess_Championship_2014

hopefully Svidler or Aronian. Kramnik and Topalov would present interesting problems for Magnus too.

I really hope it's Kramnik. In part because I think their styles will make for an exciting strategical struggle, but more importantly from a historical perspective. If Kramnik never plays Carlsen in a match (not just tournaments) then sooo many people will be saying "yeah but..." when speaking of the best players from this era as a way to diminish the significance of Carlsens accomplishments. Also, these two tied for first in the last candidates so it just feels right for them to play a match. Let that be the tie break. And if Kramnik can win this candidates (remember, there will be no Carlsen in it) then he will be about 39.5 when they play the title match. So people won't be able to claim Kramnik is over the hill or past his prime. There will be plenty of time for all the other superstars to qualify for a shot at Carlsen, now just seems to be Kramniks last real shot at it.

Although Kramnik is also reaching the age when he could start declining seriously in the next year and not be at his best, so perhaps he wouldn't be a good choice.
He was at his peak 1/2 a year ago.

tao585 wrote:
If Anand loses this match, I would consider him to be next challenger...
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Finally a vote for Anand!
People often want to bury chess champions, once they've lost their crown. I remember the same thing with Karpov in 85.
Vishy will remain a force to be rekonned with, with or without a title.
With Magnus taking a commanding lead today, we can be fairly certain he will be our next Champion. But who do you think will challenge him next cycle?
Likely suspects would include Anand again (naturally), Kramnik, Aronian, Nakamura, Gelfand, Caruana, or Topolov.
I know it's a leap, but I'm going out on a limb and saying Caruana.
What do you guys think? Cast your vote today!