I'm not sure what to think of this news.
First, is there a link to their announcement? I'd like to hear it from the horse's mouth, particularly in regards to how long we have before the d20 DCC's go away permanently.
Secondly, I'm not sure this means anything regarding the GSL. As many have noted, this could simply be due to the d20 STL approaching. That said, I'm surprised that they're just flat-out ending sales of their d20 DCC's. However much trouble it may be to remove the d20 logo (and honestly, that does seem like all it'd be - I thought you could still mention the "PHB," "DMG," and "MM" even under the OGL, for example) I think it makes more sense to do that and keep the PDFs available. The major drawback of the GSL is that you can't keep OGL versions of products published. It makes little sense for Goodman Games to dump their largest and most successful line, since there'll still be an OGL community buying the PDFs to some degree.
I'm also dubious because if they're just cancelling sales of their DCC PDFs, why not their other d20 PDFs? Are the Wicked Fantasy Factory d20 products also going away forever? What abotu XCrawl products? There's more to Goodman's d20 line than just DCC.