It's up to OEMs to push drivers or not, can't be 100% sure if v127 will be a standard for M, could happen later/earlier with a minor release or could never happen for some devices (there's a true mess with Vendors) since all the control in their hands, but I'd say most likely we'll see v127 or later with M for Adreno
As for the second part of your question:
By checking gfxbench database for the specific GPU, there you can see driver revisions and extensions that gets implemented/registered. As for Mali and upcoming driver features, it'smore like communicating personally with ARM staff on their developer forums (still they won't tell you about upcoming features plans/ETA but it's possible to monitor if something was raised for implementation/to request features if you're a developer and given solid reasons that they could agree with/get interested in), by monitoring events like SIGGRAPH and by checking documentation and release notes once new API/driver gets pushed. Pretty much it
As for the second part of your question:
By checking gfxbench database for the specific GPU, there you can see driver revisions and extensions that gets implemented/registered. As for Mali and upcoming driver features, it'smore like communicating personally with ARM staff on their developer forums (still they won't tell you about upcoming features plans/ETA but it's possible to monitor if something was raised for implementation/to request features if you're a developer and given solid reasons that they could agree with/get interested in), by monitoring events like SIGGRAPH and by checking documentation and release notes once new API/driver gets pushed. Pretty much it