I've been saying for years that I wouldn't be surprised if, eventually in some form or fashion, HSC and HSM will become a composite squadron.
However, to be tactically proficient would require more training time. With HSC sticking to PMC/SAR it would be eminently more doable, but likely shot down due to community rice-bowling as others have pointed out.
Being proficient really seems to be the long pole in the tent. HS could get away with it because the the F had fewer sensors which begat "less" sensor management which begat (relatively) less T&R (I know it's not that simple, but for the sake of brevity). Being able to make a HSM pilot a L3 in HSM stuff and then also proficient in CSAR just doesn't seem realistic in today's fiscal environment. And then there's the crewmen, who are already WAY less proficient on ASW than they should be, in large part because they aren't forced to do it enough.
Everyone says a composite squadron won't happen because of rice bowls, but I don't fully buy that. When you hear community leaders chatting (and just chatting, no planning) in their office about how FVL may require a rethinking of how the helo community may be organized, to include composites and even squadron locations, some of those rice bowls may be ignored by higher ech staffs. Especially if some of the people talking about it come from what is viewed as the more "established" community (ie, HSM).
Are there hurdles? Yup. All I'm saying is with FVL, I wouldn't put it out of the realm of possibility.
Real talk: Make the H-60 a single-pilot aircraft, put an NFO in a front seat as per RN/RAN/et al in their maritime helos, and legacy VAQ. Massive cost-savings as we cut production requirements in half and scale back the pilot pipeline, while training the NFOs with existing FRS architecture.
Again, I think FVL makes that discussion, potentially, more likely. It will be interesting to see where it goes.