So, if this happened (it won’t) and:
Enough states - including CA - hold elections. Pelosi wins, Dems keep majority. Pelosi likely voted speaker when House reconvenes on January 3rd. Becomes POTUS on January 20.
1/3
But! More Rs are up for election than Ds in the Senate.
So the Dems would have a majority if there were no elections at all and get to vote on new President Pro Tempore. 2/3
Confused yet? Cool. So is everyone else. It would be a complete clusterfuck and won’t happen. 3/3