Rather than have guest hosts, Jeopardy! will have Bialik host "more than half" the episodes for 2021. Jennings will film a few weeks' worth of shows, too. Plans for next season are undecided as yet. The game show apparently still is aiming to have Bialik host the daily syndicated show in the future, as well as primetime and spinoff specials (as previously announced).
Jennings is apparently not in the running for the full-time gig, according to TMZ, because of controversial tweets he'd posted in the past.
Sony hadn't responded to TMZ at the time of the article's publication.