It's a Google-backed project, so I'd wager the probability around "Google will add iMessage and AirTag support to Android" -levels =)
It's not really Google-backed, more Google-embraced. Google didn't even add support on their own carrier (Google Fi) until 2019.
Partial support. The full version of "messages for web" and RCS are still mutually exclusive.
my understanding based on google messaging is that google is interested but Apple prefers to have its walled garden.
Not on their own but there will be legislation. EU just passed the Digital Services Act which requires the largest of the messengers (e.g. WhatsApp, iMessage) to offer APIs for other platforms to interconnect upon request. Google could use this to connect RCS and iMessage users. Not exactly what they wanted (iOS implementing RCS natively), but same effect.
If it will take off among carriers, then yes. As things stand now it's a technology that "sometimes work".