I would like to see 14nm Excavator as well. I just don't see AMD's budget as accomodating it, unless porting to 14nm is just as complicated/expensive as porting it to 28nm minus HDL. As it stands, Carrizo has inferior voltage scaling compared to GV-A1 Kaveri past 2.6 GHz, so there's no reason to launch a desktop chip using HDL unless GF has corrected that situation through a new stepping.
AMD DOES need a test-case for GF's 14nm process, and 14nm Excavator would fit the bill for that. But does it fit the budget?