I posted something similar. Love the idea. I think the way to do it would be to make the 1st 5 prestiges all about the in game stuff that you use, weapons, attachments, lethals, tacs, killstreaks, etc. You start out with the minimal and by time you reach or finish the 5th prestige you are topped out.
For instance to start out:
Start out(you are given):2 ARs, 1 SMG, 1 sniper rifle, 1 handgun, 1 launcher, 2 lethals and 2 tacticals.
Also you are only given so many killstreaks, no aerial stuff.
Besides normal challenges and XP, you also have to complete a kill count for each gun to prestige. ARs would have a the higher kill count, like maybe 500, then SMGs at 250, sniper rifles at 50, handguns at 25. This would force players to actually use every gun at least once. And you don't max the attachments out, you get maybe like half of them. Only when you prestige do you open them all up which is the best thing, you keep the previous prestiges weapons but are alos awarded new attachments for them.
1st prestige: Again you keep the weapons from before, but are now given new weapons to work with as well as new killstreaks. Again you have a kill count for the new guns along with a lowered kill count for the weapons you prestiged with. This prestige you would get the Javelin or stinger as the killstreaks you open up invovle aerial assaults.
And this just continues until you top out at he 5th prestige which at least would make it attainable for everyone. All prestiges afterwards would be where you get emblems, titles, camo, customization and so on...which would still make it worth it to prestige without losing anything.
