His comment about not wanting to hook up Dr. Strange with the larger Avengers-verse is a deal killer. Of course Marvel and Disney want it hooked up, it's the best PR imaginable and they are making huge box office from their intertwined series of movies that all publicize each other and put butts in seats. Nobody would be doing a movie about some random Manhattan wizard if he weren't already in the Marvel-verse.
Plus, the notion that Dr. Strange somehow doesn't fit in just shows he doesn't get the character either. if Thor fits, why wouldn't Dr. Strange? Magic is not a barrier to fitting into the Marvel-verse.
This reminds me of JMS attempting to write a Star Trek show and ending up with B5 in Starfleet uniforms. Some writers bring too much of their own baggage along to be able to adapt themselves well to other people's intellectual property.
If Martin is feeling ambitious, he should convince HBO to make a space opera series under his direction, but something original, or maybe a reboot of something that needs it. Imagine what that guy could do with Stargate.