My opinion is that the question right now will not get a good answer. If there were already an answer with mathematical models and probabilities of Carlsen achieving 2900 that might be an acceptable question and answer to leave on the site.
If the question can be edited so that it's based on facts and not on opinion then it might be on topic.
I interpret the question differently, but the interpretation is, in the end, irrelevant. Even if he is asking if it is mathematically possible for Carlsen to reach 2900 (as you suggest, probably correctly), this becomes a fairly self-evident and (IMHO) pointless question. I do not see how it contributes to the Chess.SE site or model in any significant way, regardless of interpretation.