Ideally, this gamemode should have the weapons (that drop after death) despawn after a few seconds, similarly to how it's done in custmary community deathmatch servers. This would allow much greater specialization of classes, because acquiring another class's items/weapons would require a good deal of luck/coordination/timing.

I've seen people suggest adding healthshots and tag grenades and making armor specific to certain classes. These are all great suggestions, but none of them will work as intended until items despawn. Even as it is, we can already see this becoming an issue; once there are enough weapons and grenades on the map, the shotgun class becomes favored because of its sidearm. This behavior would become even more extreme if one class had armor.

PS: and since everyone else gave their two cents, here's my ideas for the classes (assuming the above changes are implemented):

Sniper: scout, molotov, usp-s, kevlar+helmet
Assault: ump, p2000, hegrenade, kevlar
Entry: mag7, p250, 2x healthshots