This is not what “control” means. Dom0 runs on your own computer and you still have full control over it, even though it’s not pure Linux. It’s just different software. It’s like saying that after installing Linux you do not have any control over your PC, because your are used to run Windows – totally missing the point.
Same about Qubes Air. You choose where dom0 (or whatever will replace it) runs and you have full control over its source code and running options, even if it runs something minimal, even if it runs in (your) cloud. It’s just a choice of the operating system. If Qubes OS 5.x becomes an OS that you don’t like, you are free to continue using 4.x, but it wouldn’t mean that you lost contol of it.
It is still a goal and I think discussing it is a good thing.