well, seeing that this whole thread is a fictitious one...
Here's the real storey behind the famous 1972 match, which have been circulating among underground chess followers for years -
The story goes that prior to 1972, Fischer played Spassky 5 times and never even came close to beating him...yet Fischer beat Spassky like a drum during the WCC (even forfeiting one game), Spassky also conceided to every wish that Bobby requested, aven though he could have easily won by default. Why would he have done so?
The rumour is that Spassky planned to loose to Fischer all along, this would have resulted in his lost of prestige in the Kremlin, but would have easily paved his way to leaving Russian Supremacy for more humane conditions in France. His plan however took longer than he expected, and he was only able to settle in France with his family in 1976, and granted citizenship in 1978.
Fischer was actually informed of the "tank" by Spassky, and was too humilated to say anything about it (since all along he and the rest of the world thought he had actually defeated Spassky), he clearly was no match for Spassky, and obviouly no match for Karpov (who was even stronger than Spassky)...so he did the only thing he could to preserve his status...he disappeared...he did however, resurface to face Spassky in 1992 to prove to Spassky that he was the better player...he did, but his victory was bitter sweet, since it was obvious to everyone that Spassky was no longer interested in chess.
Bobby's personal diary details all of this, but is closely guarded by his family to preserve his integrity.
And I think the only reason Anand, Carlsen, and Aronian would score well against Fischer is because they came later in time.
I'd have a hard time believing any of those guys would score well against Fischer if they were all contemporaries. They are all obviously elitely good at chess but have any of them shown Fischer-esque brilliance? Russian champs, ex-champs, and contenders were already conspiring against Fischer when he was Carlsen's age.
Carlsen may still be young enough to win the champion but every missed chance to play in these world champ events is costly. Younger GM's are cropping up, he needs the experience to beat the older crop, and his younger contemporaries (Aronian, Radjabov, Mamedyarov) are all gaining that experience while he sits.