I don't see a problem with a QEMU-only OS. Serenity is explicity designed for personal use. It's not a headless OS in any way. I could see it being useful in a corporate environment where it's useful to have a windows host for business reasons, and you run your unix-like system in a hypervisor for development. That's how I work, and I think quite a few people work like this. Serenity is perfect for this.

And obviously, nothing prevents people from writing drivers eventually. Andreas probably wants to run Serenity on whatever his hardware is eventually. But there's little point in doing that till we actually have a mature system that anyone would want to run daily.