It's been ten years. It was designed before the iPhone caught on, before OTT services took over the world, as a way for carriers to "fight back" against OTT. This "guy named Dean" has been covering RCS for 10 years already. Read the whole thing. RCS "usage" numbers are heavily inflated, it's all hot air. The whole thing is full of fundamental problems, one being Apple having zero interest in supporting it.
In 10 years, only 49 carriers implemented RCS, many are incompatible with each other and some even silently dropped it. Many smartphone manufacturers never bothered adding support for it on their phones (it's not just a software update).
The rest of the world outside the US moved away from SMS and RCS won't bring them back. At best, what happens is that US Android users will get slightly better messaging among themselves via the default texting app. Texting with iPhone users will still be limited to 70's era SMS tech and 80's era MMS outside from OTT apps like Messenger. The rest of the world will keep using whatever OTT service gained popularity in each particular region.