I'd suggest building an auto-upgrade system on top of Arch (or Alpine), and go for immutable infrastructure as the selling point. That's stepping on CoreOS's toes a bit, but I haven't seen any progress from that crowd ever since Red Hat bought them, so it'll probably get even worse now.
That way you can target AWS/Azure/$OTHER_MODERN_STUFF in a more focused way, and you won't be stuck on supporting months/years old versions of the OS.
In that case, why not go all the way over to NixOS? They already have a more or less complete cloud stack with NixOps, the only problem is hardly anyone knows how to use it.
That's a massive, show-stopping problem.
How so?
I agree that it's a nontrivial problem to learn a piece of complex software from scratch to the point that you can offer comprehensive enterprise support for it, but how is that show-stopping?
I'm not sure what the cause is. If it's a fundamental technological problem, then it's insurmountable, but if it's just a documentation problem, then it might be fixable. It doesn't look good though, since, like I said, the whole stack has existed for a long time. You would think that something would've been done about it.
All that said, perhaps I'm just dumb. I'll be happy to see someone prove me wrong and succeed with that combo. The underlying technology is certainly interesting and powerful. But I won't be trying it.