While there's definitely a large amount of politicking involved in getting term limits removed, I'd like to think the meritocracy system on which the CCP operates on is what keeps Xi in power. The west sees it as autocratic oppression, but the people of China and the party see Xi as a legitimate leader with a proven track record. The country and the party will rally behind Xi, much like how it did with Deng and (to a certain) Mao.Now if Biden wins (as he's likely to), how would that change the potential impact of Xi serving a third term? It would be less of a problem if Trump wins as Trump would provide a cover by getting all the hate. Xi almost have to serve a third term as all members of Politburo Standing Committee are of his generation.
If we are to draw parallels to western democracy - Merkel's been Chancellor and Netanyahu's been Prime Minister for over a decade now. I can't see how Biden's win would affect Xi.