What sources inspire anime best?
Light Novels: 48/200
Visual Novels: 23/200
Video Games: 8/200
(This adds up to over 200 because some franchises have multiple sources from multiple mediums)
Manga still has the sizable advantage, but light novels are creeping up on second place, just behind original works. Visual novels come in a distant fourth and video games an even more distant fifth.
It's my contention that the future of anime will be mostly split between light novels and original works. Manga isn't inspiring anything good these days, visual novels are hard to adapt due to the branching plot paths, and video games don't make for very good plots because they're built around fun game mechanics not story lines.
But the only way to change these numbers from here on is to shove some other series out, so it's going to get a lot more competitive from here.