I wouldn't hold your breath. Sales people will tell a customer what they want to hear in order to get them into a showroom.
I would guess if it were true there would be "spy photos" of prototype AVs in the usual "leaked" car photo websites and hints from moto-journalistic websites who get insider info and then maybe a grand unavailing at a large carshow or if marketing has the budget a hint/sneak peak commercial to create excitement and test the waters of customer interest.
It seems though that all we see are old photos or stories rehashed showing things like the accessorized Silverado or some smaller concept AV looking like a modified Colorado platform..
Yet if they can keep building the Suburban there is the possibility of a full size AV as discussed in many threads since the AV stopped production. Seems like someone being optimistic starts a new thread each model year with rumors of restarting the production of the AV.
I wish it was true but realistically doubt it will happen. I also will predict if it doesn't happen in 2017 there will be a new thread started saying it's coming back in 2018......