I'm not sure I'd like html apps as an alternative to an opengl framework. I developed a few html apps, especially for prototypes or internal apps. I also have NativeScript and React Native in production. All of them have pitfalls, performance issues, missing native plugins (or very badly developed ones).
There currently simply is no good (and free) eco system to switch to.
All try to reinvent the wheel for no reason.
I'm fine with Adobe Air just receiving maintenance updates. It's a solid system, it doesn't really need AS4 just for the sake of change.
Don't forget that also major big players dropped their flash products entirely, most notably Scaleform! Which was always an argument for me to say "they wouldn't drop AIR support while a billion Dollar business like Scaleform is still there".
As a company I wouldn't bet on Adobe in the future. It is also very hard to actually find employees in this field.
We for example found a single Starling developer as a freelancer in the past two years. I'm currently managing Starling apps that have 2m+ users, entirely alone, because I can't find help. Doesn't do wonders for my vacation planning (my company pays me out instead of giving me vacation atm). Does do wonders in salary negotiations though π