I love the idea of upgrading SMS (after decades) to something more modern and useful. This is why Whatsapp, Telegram, Signal, etc became so successful.
But for it to become really mainstream (and possibly dethrone some of those other messengers) it must be:
1. An open standard for use and compliance by all so that there is interoperability (unlike every other messenger). It cannot be owned by Google or some closed consortium (apparently it is open but 'Google with partners' does not sound neutral enough).
2. Needs to work across all devices including Android and iPhone. We don't need yet another iMessage service.
3. Needs to be truly End-2-End-Encrypted (as in user-2-user) and this is where the issue will come in as right now SMS is open text that any government can read remotely. Why am I thinking the US, China, and others won't like this unless there is a backdoor...
See Helping you connect around the world with Messages
Messages expands RCS messaging and provides added security protections in chat conversations with end-to-end encryption