Updated the OP with a little more info
Anyways, my thoughts about random weapon spawns:
What if power weapons do remain on the map like in previous Halo titles, but with the occasional random weapon drops to mix things up. This is what I imagine is happening, but time will tell.
Also, I assume not every weapon will be available to spawn with, and spawning weapons will be guns like AR, BR, DMR, Carbine, etc while guns like shotguns and snipers will spawn on the maps. If anyone can spawn with snipers, rockets etc then I am upset, otherwise I like it. Gears 3 handles it pretty well, and I assume that is what Halo 4s system will be similar too, only with CoD style unlocks.
Maybe it will be like this:
-Starting weapons (customizable and unlockable)
-Map weapons (set spawn points and times, guns such as shotgun and sword)
-Random Power Weapon drops (guns such as Rockets, snipers, etc)