I've maintained since he was elected that he was nothing more than a way to backdoor Harris into the Oval Office, giving her the big chair for a decent span of time while still maintaining her two-term eligibility after. Basically a way for the Dems to get a three-term President who ticks a bunch of their "equality" boxes.

I further suspect that, if she doesn't completely suck at the job (or even if she does, but they can pin most of the blame for it on the Republicans), they'll try to spin her terms into something of a dynasty, with her giving the nod to her appointed successor--like they tried to do with Obama and Clinton before--and the Democrats then presenting that to voters at election time; "Kamala Harris approves of candidate "Y," and you wouldn't want to go against our extra most bestest president, right?"