If the Joint Combat Pistol/Combat Pistol (CP) solicitation from 2006 is any indication it will have to be a production pistol. The military isn't interested in funding an R&D project.
The Glock 21SF wouldn't make the cut because they don't offer an external safety as the CP spec's require. Based on the pistols entered into the CP competition, my vote on the front runners would be the HK45, Sig P220 Combat, FNP45-USG, and the S&W M&P 45.
That solicitation didn't last long before they pulled it because for the most part, what they were looking for wasn't really out there.
If you ask me, the 2006 solicitation was to plant the seed, let manufacturers get such models going, and the the military will give it a few years for the competition to weed itself out, leaving the strongest for the next round of solicitation.
I supspect the next one will be very similar to the last, but may have a few differences.
