Observing my own behavior, I think there's going to be a trend where people will use multitasking to avoid pre-video video ads. Unskippable 30 Second Sears Ad? Ok, I'm gonna go do something else, then hop back in a bit. (Of course they still have my ear, and also that might lead to an escalation where videos autopause when they lose the focus.)
I know some folk use AdBlock, but I think that does too much. I enjoy a lot of content for free, and don't mind being some part of what keeps that going -- it's a question of where the line should be drawn, and how.