I think the bigger problem would be, would they be willing to invest the engineering resources to do all that.

If the crux of the argument is that WP Engine doesn’t give back, I wonder how likely it would be that they’d be willing to do that.

Of course, if they were willing, they’d be allowed to do that and might even find success. I’ve often wondered why a host hasn’t tried to do a more focused WP-fork and the main conclusion I’ve come to is that they just aren’t willing to invest the significant resources that that would require.

It wasn’t a host, but CraftCMS was born out of ExpressionEngine (not the code; the Craft code all unique) and the makers of the most popular EE plugins being frustrated with the core EE direction.

Craft has a thriving business and EE has been sold several times and is much smaller than it was, so it ultimately worked.

But that was in some ways the opposite of this scenario; you had some of the largest ecosystem members who were unable to contribute meaningfully to core (because of the license/structure of EE at that time), opting to do their own thing.

I don’t anticipate any of the major hosts willing to invest what it would take to build/maintain their own WP fork.