It's not that they won't make the jump, but that they're not trying to. Videos of the kind "YouTubers" make have evolved into a distinct media genre separate from episodic television. Your statement is analogous to saying "comic book authors won't jump to writing novel-ready content" -- of course not, or at least, not in a way that implies the latter is a progression from the former.

And a corollary: genre is distinct from delivery mechanism. "House of Cards" is a TV show and Jenna Marbles videos are (for lack of a better term) YouTube-style videos, even though both are delivered via the Internet.