Not really, up ammo crate drops on all difficulties and make them fairly common. The whole idea of an endless wave is that eventually you get overwhelmed by sheer numbers, not because you ran out of ammo. So they could just litter the map with ammo crates.
I like the idea that you just find weapon upgrades while roaming around the map.
But I also like the idea that the trader opens up while zeds are still coming and people have to quickly buy their stuff while others watch their back and wait their turn.
Id rather not have breaks between waves though, I want one long endless wave where the spawns (fp/sc) are determined by the timer.
The way infinite wave modes work (Think Nazi Zombies, or whatever the hell it's called now) is that every wave zombies come at you. With each subsequent wave, the zombies get more hp and are more numerous, with a breaking point deciding that they can then sprint.
The issue I was trying to highlight here is that this can't work in KF2 with the current mechanics; your solutions do nothing for this.
Having ammo drops everywhere doesn't encourage strategic play; you have infinite ammo, just unload everything you've got! Oh no, you ran out of microwave gun ammo? Evidently you didn't, because the map is littered with more.
Having the mechanic be based on sheer overwhelming numbers is impossible when a microwave gun or molotov or medinade can kill a group of over 10 zeds using the same amount of ammo as it takes to kill one; unless you're throwing lag inducing incredibly absurdly large mobs at us it doesn't matter how many clots you throw my way, especially if you give me infinite ammunition.
Nazi zombies is balanced around having weapons scattered around the map that can be purchased at will along with their ammo, with an additional wildcard of the mystery box. This keeps things tense in a way that works with it; at wave 30 it doesn't matter what you've got, the zombie's HP is far too great to get an instakill. If you just go for a billion clots and gorefasts as the way to overwhelm players, while throwing ammo packs sufficient to allow victory around the map, you're gonna find that the only time anyone loses is if they go full moron.
An infinite wave mode could work for KF2, but definitely not along the lines you're describing.