the way I see it, physical buttons have two uses one is tactile navigation: the ability to find out what part of the screen you're touching and navigate it without vision.

the second use though is activation feedback, a button has to be able to be navigated separately from its activation. unless these protrusions can tell whether they are pressed or not, it still seems useless to have a lumpy touchscreen...

so I really hope they found some method of separating simply sliding a finger around searching for a button and realizing when the finger is pressing down... this is the exact same issue as the various touch-mice devices

(left click with finger on left side, right click with finger on right side, unless that is you like to REST your fingers while clicking)