Encryption is supposed to come when the working group has aligned.
I wouldn’t hold my breath.
The whole RCS thing is a Bad Idea™ . It’s a standard by the GSM Association, which consists of over 1150 members (750 operators and 400 other companies). Getting all these companies to align will take forever.
To illustrate: the RCS initiative was started in 2007 and the steering committee was formed in early 2008. The first version of the Universal Profile, that would enable interoperability between different operators and networks was released in 2016. It took 8 f-ing years to come up with an interoperable messaging standard to replace SMS. It was intended to be implemented by operators, but since hardly any operator did Google had to run their own service, bypassing the network operators, just to get it off the ground. Operators are now slowly beginning to support it.
If Apple decides to add a feature to iMessage, they implement the feature, roll out an update to their servers and release it to a billion users in the next iOS update. If they want to add a feature to RCS, they first have to discuss it in the committee until they agree on a solution, this alone takes forever. Then every player needs to update their software to add support. This means potentially 750 operators who need to update their shit, and that is after their software suppliers add support for it. In the mean time, the new feature will work for some users when they communicate with some other users, depending on which phone and operator each party has. Rinse and repeat for every new feature you want to add.
This means RCS will at best only ever be a very basic messaging service. It’ll be an improvement over SMS and MMS, but that’s not saying much. It will be in no way a threat to Apple’s dominance in messaging.