Seems like this will be 12-18 months out for the commercial market and I'd guess 2-3 times the price of the 716. There's certainly room for both in a lineup and probably not a whole lot of cross shopping customers.
They say prototype but in Sig talk we all know that means it is ready for release to the public for beta testing. Make sure to buy the gen 3 after they fix the gen 2 which fixed the gen 1.