You know the freakiest part about Carlsen? He's still only 22 years old!!
His best is yet to come!!
If I was Mag and I was able to win GM, I would go on a prolonged hiatus of like 8 years then I'd come back and see what the competition is. but don't pull a freaking Bobby Fischer and ignore everyone, but just go and teach then come back at like age 32 and give it another throw
Maybe not the greatest, but yes.
When he beats Anand in a match then i'll probably say he's the greatest.
If he beats Anand and defends the title for for years like Lasker then he'll be the greatest.