While taking 4 700's don't make sense right now there are routes that Delta still needs covered and the 700 is the best airplane for the job. Key West and the Bahamas are airports that come to mind. 3 flights a day are done between ATL and EYW by ExpressJet currently. Why? Because mainline does not fly into EYW at night. Is putting a 900 into a 4800ft runway possible? Sure. Is it comfortable? Not really.
Could we be getting more 700's in the future? All signs point to yes, BUT the only realistic place they could come from is GoJet. If you thought the ExpressJet 200's/900's were in bad shape..... At a certain point the cost of moving airplanes from one certificate to another becomes too costly. I've bought into the hype before (E175's done deal etc.) but I do my best not to get folded into rumors anymore.