Hmm.
So, if it's a property that at least somewhat resembles D&D -- Princess Bride is a good suggestion -- it could work. Not sure that WotC has the bandwidth, especially now, to take on more work and either pay a licensing fee on the final product or split the profits.
If it's a property that requires them to make a modern day or science fiction ruleset, then absolutely not. Too much work when they're not getting 100% of the revenue stream.
This is the kind of thing the OGL is made for. If the Princess Bride license holders (who love licensing out the movie) want an RPG (in fact, wasn't there supposed to be one at some point?), they can just use the OGL to do it and leave WotC out of it.