I switched to Dvorak at the same time as switching to a split, columnar keyboard. I have never used Dvorak on a traditional staggered keyboard, and I have never used QWERTY on a split columnar keyboard. By separating the layout usage on such distinct form factors, I haven't lost QWERTY even after not using it as my primary for years :)

I also do still use QWERTY for touchscreen devices, because you can't keep your hands on the home row on touch screens, so you lose the benefits of Dvorak (and I actually found the common letter combos being near each other to be way more cumbersome on a touch screen).