Interesting that (A:cannon ammo ,number ) is still a useable variable in MSFS. I'm thinking that you will get something like you get with elite dangerous. If you have the "Shooty dakka dakka" DLC then you can on a separate server with other shooty shooty dakka dakka DLC users to have the combat experience.
My understanding is that the ban on weapons in MSFS DLC sold via the marketplace is because adding weapons has the potential to change the PEGI rating, which then changes where and how MS/Asobo are allowed to advertise the product, so I'd be surprised if there was ever any "official" content involving weapons.