Have you guys seen the metal storm company? their maul shotgun is essentially a barrel with a trigger-with all the shells stacked in the barrel and fired electronically. Compared to other under mount shotgun systems its exceptionally small,sleek, and is semi automatic. I think if they could create a very compact unit that had a very small fold up stock and a quick detatch mount, so you could easily switch from and use the maul as a stand alone or under mount attachment it would be ideal for todays combat situations.
at least for Canada and its allies, we are capable of being very effective at longer ranges, which is not something that many of the opposing forces we may face can. As such, shotguns are a niche weapon, and having something that is sleek, portable, and able to work alongside our other weapon systems without competing will be the future.
also, another thought on a hindrance shotguns have with specialty rounds that keep them from being as big of a benefit as they should be. Shotguns have a lot of different rounds, allowing one weapon system to tackle all sorts of situations, including lethal and non lethal. This should be a benefit, but there comes safety risks when using a firearm loaded or previously loaded with lethal rounds, and most op for a totally different weapon to handle each round. Would there be a way to create a shotgun system that can determine the type of ammunition loaded, and would only fire when both the shell and shotgun was set to that particular setting. I am thinking perhaps a groove on the back of the non lethal shell, and a spring loaded peg near the firing pin. If the groove is there, the peg goes forward, allowing you to fire when in the non lethal firing mode. If a non grooved lethal round is placed, the spring would stay depressed and it would not fire. On electric systems round detection would be even easier. Just having a small non conductive material on the shell brass and a simple circuit inside.