You herd the group of cats that are all my friends, family, and work colleagues and get them to use a standard app that's not Facebook Messenger. π You'll have to forgive me if I don't wait.
RCS, seriously? Not sure how that is outside the US, but it's a total non-starter if you're not using your phone in a Google-blessed configuration. Rooted? No RCS for you. No Google Play Services? No RCS for you. Don't like "Google Messages" and want to use any other messaging app? Believe it or not, no RCS for you.
Maybe if the day ever comes where Google is excised from the RCS infrastructure it'll be a viable option, but as it stands ( at least in the US where I have experience with it), it's definitely not a replacement for SMS.