I don't think we'll be seeing STM used in L-series lenses. AF during video is a consumer 'feature' - pro video shooters focus manually (often with a whole host of accessories to facilitate that - looking at a complete dSLR video rig, it can be hard to spot the camera!).
According to the professor at RIT's Imaging Arts & Sciences school that I asked, that isn't always true. For documentaries, where subject/talent motion isn't tightly controlled, AF is routinely used. Where the motion is controlled, yes, MF is used. At the time, he was conducting a shoot with two of his students at a local historical village, using a Canon XF305. Because of the subject matter (static Civil War cannons being fired) AF was used to set focus, then MF was used to hold it. Without MF, the camera kept trying to shift focus from the Cannon to the smoke.
Some high end camcorders do have autofocus, and for TV and documentaries, they use AF.
However for Cinema or high end commercial use, the use of autofocus is rare, in fact, few if any Cinema cameras or lenses have autofocus. I don't think Panavision makes a autofocus lens, for example, and the Zeiss Compact Primes are manual focus. Sometimes there is a bit of footage inserted into a movie taken with a camcorder, but its not the rule.
Its just a matter of what level of professional use you are dealing with. Does the professor belong to ASC?