I think when Casas is ready, he's going to be on the 26- maybe even this year.
I think a free Hosmer will remain on the 26 for much longer than some expect. Of course, if he slumps, that changes. He was literally, the poster boy for up-and-down seasons over his first 8 years in the bigs: odd-good/ even-bad or so-so. Since then, he has a .743 OPS (2019-2022.) While that is not what we hope to expect from 1B, it's not awful, either. (162 avg was about: .270 20 90 w 50 XBHs.)
I can see both being on the roster for a while. I don't like the idea of Hosmer at DH, but I get the feeling we will have to go "light" somewhere in the line-up, and DH might be the best choice, in terms of flexibility and the ability to easily fill via mid-season trade, if needed.
We may choose the catching position (McGuire/Wong/RHern), 1B (Casas/Hosmer/Dalbec) or 2B (Arroyo/Downs) to go light, but I think 1B/DH will be Bloom's choice. I think we add, at minimum, a Catcher, 2B/SS, CF, RF and Pitching.