perhaps, but...
You can expect to see the US military using the M16 up into the 2020s. Rifles have a way of getting ingrained in the Service, and the military has already said they won't adopt a new weapon until there's a "significant increase" in its abilities. It's a shame, too, as there are some rifles that are a lot better than the M16, but that's another matter altogether.
Anyway, a caseless rifle really doesn't give the individual shooter a big advantage over the guy with the M16 or the AK-74. I've been turning over in my mind what guns will look like in 50 years, and have come to the conclusion they won't be too different.
IF the military adopts a new rifle in the near future, it'll likely still be chambered in 5.56mm or some similar caliber, but there are some advancments you might see.
-Lighter, stronger, more use of advanced composites like carbon fiber. Professional Ordnance already produces an AR-15 variant that weighs 3.9lbs.
-You might end up seeing a weapon that's completely nonmetallic, but that would require a significant advance in materials technology
-synthetic bullet casings, new propellants. Perhaps they'll be able to make a cartrige with a case length of, say, 25mm that performs the same as 5.56x45mm.
-Internal recoil absortion. The Russians have already experimented with this in their AN-90 rifle prototype. Imagine being able to fire something chambered in a full power rifle caliber on full auto, yet being able to keep the sights on target with no loss of accuracy.
-Advanced sighting technologies. You may see, in the future, a device that is as compact as a typical modern rifle scope, but can zoom in and out, has night vision or infra-red, automatically corrects its zeroing for the distance of the target, a built in laser rangefinder, and stuff like that. I just hope they don't forget the iron sights! EMP weapons will become common int he future, and it'd be a shame to not be able to use your weapons because your platoon got hit with one measly EMP grenade!
Aside from that...in 2050, assuming the laws havent' gotten out of hand, expect to be able to walk into a gun shop and be able to pick up a 1911, a Winchester 94, and an AR-15. Some guns just never go away!