If (and obviously a big if, and just my opinion) they launched new mods and kept them like zetas (no way to straight up purchase). I think we could be ok.
Mods with speed secondaries will still be king and even a +12 would have a good shelf life.
They could also only allow them to be put on g12+ Characters, which would help to stem the tide a bit.
I think an upgrade system is an interesting idea, but may not be viable due to the increase in p2p/f2p gap it would cause. Still this would be a viable option to examine.