The situation was resolved by Google taking effort to unify the Android landscape and maintain a single client for that OS, instead of carriers (like Orange Group) developing one client, Samsung, LG, Sony, Huawei, ZTE each developing other clients
Google doesn't own the RCS-specification, the spec is still defined and maintained by GSMA, with Google just having one of the seats at the table (along with carriers and device manufacturers).
Apple is also a member of GSMA, them adopting RCS means that they just take another seat at the table of the RCS working group.
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> Google has significant incentives for pushing RCS for more than one reason.
I don't know if you mean to imply some hidden Agenda. The incentive is to standardize "rich communication" across mobile platforms. "Green bubble" is one manifestation of the bigger issue that 27 years after the creation of SMS there is still no other universal method for me to send a text to your phone number today.
The main reason for that is, that several players still hope to own this communication channel to the user with their proprietary app, become the "Western WeChat" and sell access to the users.
RCS could be an universal non-proprietary method, open to be adopted by Apple, Facebook, WhatsApp and whoever wants to build a Message ecosystem. It has the potential to end this hassle and allow me to send a text to your number and reach you regardless of your OS and application of preference.