I've agreed Casas and Romy start the season on the IL and there is no need or rush to trade Masa, now.
I don't see him "blocking" Eaton, either.
KC will begin the season in AAA, and he won't get the call, unless it's to play FT or near FT, so in that context, Masa is not blocking him, until (and if) he has proven himself to some extent, but then again, Masa kinda has to re-prove himself, too, and with Duran at FT DH, that will be hard.
To me, it's not so much about blocking KC & Casas-Romy, it's about having 4 FT OF'ers and using a bench slot for a DH only player who likely needs to be platooned.
Yes, we may not not have to do anything, even until June or the dealine.