PowerApps is currently more flexible and extensible than AWA's ever were. Granted that doesn't make them a viable replacement for AWA's either, but AWA's were doomed from the beginning by the box they were put in to begin with. The train went from Station A to Station B and stopped there. PowerApps has the Power Platform ecosystem behind it including the ability to consume Public APIs and connectors to over 300 different data sources, not just SQL Azure, as was the case for AWAs.
It's interesting to speculate what AWA's could have evolved into, perhaps something more like PowerApps already is, though?
One thing that tickles me is that PA was originally touted as a "low-code" platform. Yet over time that has evolved into "less low" coding. Today, for example, I saw a YouTube video on creating UDF's for PowerApps. They walk and quack a lot like simple VBA Functions, taking input parameters and returning output parameters OR executing actions like VBA Subs. What that tells me is that the Power Platform development team recognizes the need to push their platform beyond its early "no-code/low-code" identity.
Again, that could have happened with AWAs, of course. What did happen was a new platform was built from the ground up to be browser based from the beginning.
If it were not so costly to license, I'm convinced PowerApps would be a more popular option.