I don't think RCS is the end solution, just as Signal isn't. Both are hopefully just gap fillers for a more decentralized way of communicating securely and privately. But I agree that RCS appears to be better than the current model.

The problem for me is that I haven't found a decent FOSS app that supports it on Android, meaning I don't use it now even though I could be. Back to the same problem unless it becomes decentralized enough that I'll use it. I'm not using Google's closed messaging app just to have RCS. I'd rather just not text or hardly do it.

I'm right back in the same boat. That's why I think the best solution is to have a standard, decentralized protocol that is compatible for all of us and easily available for FOSS use.

Maybe RCS will become that in time. It's relatively new compared to standard SMS.