I'd go for something broader that's bound to satisfy and reward lifetime players for staying around and being active (which in turn provides more activity for monthly paying customer) by the way of a monthly-given cumulative Cryptic Point budget.
It's not something that can be given away afterwards to monthly playing players so it should remain 'exclusive'; it's something which can be used by Cryptic to have Lifetime players 'advertise' thier C-Store product; and it's a lifetime reward that probably will turn out pleasing every person that invested in a lifetime subscription (because - honestly - none of the lifetime rewards since launch have appealed to me).
Turbine does something similar to their founding lifetime subscription players regarding their Turbine points. I see it as a good practice.
Other than the liberated Borg character, there really isn't anything yet that stands out as a "must have" to entice people to get the lifetime sub. Now if you give lifers exclusive access to a special store where they can spend their GPL on Purple Borgified gear of any level, then we are talking.