Never gonna happen!
The signature rules were made all the way back in 2001. It makes ATRL much better to cut off the signatures at 7 lines and make it so pictures and videos can't be in them. Signatures with large text and pictures are distracting and messy.
That's also why smilies were removed from signatures more recently--in the "old days" we only had tiny smilies, but now we have some pretty freakin' giant "smilies" as well, and people were littering their signatures with these giant images.
BTW, to illustrate my point...
You think somebody wouldn't do this? Oh, they would. Even if only a few people did this, it would be annoying as hell and everybody else would go deactivate signatures entirely on their
Options page.