Scott,
There still needs to be some way to control compatible products and give them compatibility language. Without it you have anything and everything claiming 4e compatibility, which is bad.
The real question is: Will D&D 4e have the D20 logo on it?
If so, then I think you need to give the 3rd party OGL products that want compatibility with D&D4e the ability to use that logo too. Completely removing the current system I believe is a mistake, as it opens the door to either a) any product being capable of saying it is compatible with 4e or b) having to put a subset of legal rules in the OGL that grants the "compatible with 4th edition of Dungeons and Dragons".
Personally, I think you should do this:
1) Have the OGL for 4e and keep SRDs updated with every product or at least the main ones. Allow some sort of compatiblity language but no brand usage.
2) Have a paid D&D 4e liscense that allows companies to make their own IP based modules, campaigns, etc. The paid license has very tight quality control, but grants the official D&D logo, ties the product game mechanics into the D&D Insider and makes the material official. The standards for this level should be high. This approach treats the D&D products like a game system (think xbox 360) and then the 3rd party licensed companies as game publishers. Make the fee high enough to keep those who can't put out good quality out of the game using the OGL. These products get the official WOTC approval logo and the D&D logo put on them. These companies can use all of the published D&D books and refer to them as WOTC can, they get the designer rule & style guides too. Control this with NDAs.
Anyrate, there needs to be some way to say here is the OGL stuff and here is the stuff that followed our standards and used the official rules. Anything that can put "compatible with the 4th edition of Dungeons and Dragons" or " Requires the 4e Player's Handbook for use" needs quality control on it and in turn should be granted brand tie in in some fashion. This is what you are potentially taking away and not replacing with something comparable. That is not a good thing.