Prestige is an interesting idea. Not sure what it would solve though - we already have directives to give BR100s something to work on. And BR100 takes a lot longer than CoD prestige (from some quick research, and the fact kids I teach regularly brag about their prestige ranks the week after a CoD game is released).
Even so there is little reason not to give the games dedicated players who reach BR100 more stuff to do personally beyond Directives and further advancement would be interesting. Having a reset for certs is interesting, but when you are talking hundreds of hours for decent SPM players and potentially thousands for the average to reach BR100, giving up all those certs is going to be an incredibly painful process for many that toiled long and hard to get them. Don't forget that in CoD it is you and your equipment - with a handful of classes - but no vehicles to certify into. Sure keep the weapon unlocks but I'm not sure. Saying that I would very likely go for it and burn my certs to get an extra shiny thing.
However, what I would like to see first is the directives system fixing - too many of them are near to impossible to achieve in any reasonable time frame - especially with some weapons and balance the way they are. The thing that springs to my mind is my personal quest to get HA Auraxium - I have all the LMGs and Lasher auraxiumed already, yet the remaining few I need for the auraxium (AV Grenade kills, MAX kills, Air Deterrence) are ridiculously hard to get in general play. With many directives as Higby mentioned before leaving we need to get them converted over to XP earned, so that the hard-to-get-kills-with weapons become easier to earn some credit for realistically.
Black Ops is a solid idea, although I would like to see rewards include NS armour for the character to use to make them really stand out beyond plastering an NS logo on their empires armour. They should also get to use the empire they are supporting's arsenal, so that you never really have to roll another character if you do not want to and really play the mercenary.