Porsche is going to hook up with Red Bull. Porsche is exploring the possibility of buying 50% of Red Bull (news leaked after a formal filing in Morocco, of all places, was revealed). Porsche will also supply AlphaTauri, but one has to wonder how long they will be willing to keep owning that team as well.
Audi is most likely going to buy Alpha Romeo, which is just Sauber with Alpha Romeo sponsorship. It's not a factory team at all. It will be once Audi buys them. They will buy 25% stake each year for three years, leaving Sauber to own 25%.
Both of these moves are dependent on the FIA finally, officially approving the engine rules for 2026.
Honda is reconsidering their move to leave F1. Typical Honda. Who they will hook up with is anybody's guess. Williams and perhaps McLaren (how ironic) are the only real possibilities. Haas still seems too attached to Ferrari. But money talks...
Andretti wanted to buy Sauber. Sauber upped their price when Andretti thought he had a deal. Now, Andretti wants to start a team from scratch, but currently does not have the support/approval of the FIA and the other teams. If he does, it is no secret that he will hook up with Renault (Alpine) for their engines.
The original reason to rename Renault to Alpine was to promote that brand as their performance brand in Europe. So, ultimately, it's up to Renault to decide how best to market their brands.