Sponsorblock would be easy to work around if ad-breaks were randomly selected. Whenever you upload a video YT could process the video and "search" for good ad-break locations, at display time client bits get pushed ads randomly, making time-code blocking useless.

They could even upsell to content creators by giving them the means to dynamically replace sponsors in old videos using the same tech, maybe with some knobs and switches for content creators to select where sponsor breaks occur.