I said it before and will repeat it. Biden will be president through the '22 elections. He has no choice. If Kamala becomes president, then the VP seat (and the associated tie-breaker in the Senate) goes away until the Dems could nominate a new VP and get it to gain Senate approval (which you know McConnell would hold up as long as possible) and thus stalling or thwarting the passage of any lefty legislation until this is resolved.
Not to mention the likely scenario that if Kamala becomes president, then the leftist pivot would likely lead to even greater losses in the House and Senate in the '22 elections. But after the '22 elections, then it won't really matter who wins the Senate in regard to appointing a new VP for Kamala. If the Dems win it, then they appoint who they want without issue. If the Repubs win it, then two possibilities: 1) Biden resigns between the election and new Senate taking over or 2) the candidate will have to be a more moderate Dem, but there would be limited value for McConnell to stall the nomination given the VP tie-breaker won't mean much with him in control of the Senate.
But I do expect she takes over after the '22 elections, then it serves as a de facto trial run for her and the Dems going into the '24 elections, so they can see if she's viable at the top of the ticket or if her 2% primary result was more reflective of her true national appeal and she'd need to be primary-ed.