Hope you're ready for some disappointment... It's 1/180th without a HSS flash on the hotshoe.
I agree with you totally, they could and should implement an electronic shutter, or a hybrid shutter. And it wouldn't need to be limited to a mirorrless body either.
Currently if you want faster than 1/180th with K mount lenses without having to resort to HSS, you'll need a Q with a K to Q adapter. That has a 1/1000th leaf shutter built in, but unfortunately you'll have to put up with a 5.5X crop factor.