My impression from the phone call was that 4th Edition will have it's own license, which they were calling the OGL, despite the big differences.
During the call, I pointed out that they had told us that there was going to be no D20 STL, only the OGL....but that in the call, they revealed that the restrictive parts of the STL (content guidelines, requiring the PHB, etc.) were going to be in the new license -- meaning that really, we had the opposite: A d20 STL, not an OGL.
The response (from Bill Slavisek, I think -- I'm not good with voice recognition) was (and this is a direct quote): "Well, that's one way you can look at it."
So it appears that the new license isn't really "open" -- it applies only to D&D, indicates compatibility, has content and taste restrictions, requires the PHB, etc.
The original OGL is perpetual, however -- and there's nothing stopping someone from publishing Fantasy material that could easily be used with 4th Edition, as long as they don't use any specific-to-4e rules, and as long as they don't claim compatibility with D&D, which will be an exclusive pervue of the new license.