I'm sorry, but it seems the demographics are no longer with you on this one.
Let us review: (
WotC - Comparing EN World's Demographics to the D&D Community's)
As you noted, Greyhawk material was already waning by 1985 - that was 35 years ago. That means that Greyhawk fans are generally in the 40+ age category... which seems to be around 11% of the current D&D player base.
Greyhawk fans may be vocal, but they no longer hold dominance of gaming's economic pie. It hardly makes sense to put such resources to a project targeting them, considering how critical you note they are.