Thx for interesting thread m8.

Yes i think its possible but only if state dose something bout it and presses acedemia, media, etc. However if we replace -ma with -h that would mean you wouldn't have -ma anymore, or?

If that were to happen, because *-h is the original ending of locative plural case it should replace *-ma only there.
So, instead of "voziti po pravilima" we would get "voziti po pravilih", the way it should be =)

The *ma ending would definitely stay in instrumental, because it is the ending of that case.

Dative plural would be a tough one to solve…