The reason the current Veteran rewards program is being ended at 1,000 is that each tier is just as much work as previous tiers, but is less incentive for new players to subscribe. 1,000 days is a long time for most people.
It will undoubtedly be replaced with other systems for encouraging long-term commitment, which hopefully do more to encourage new Lifetime subs. (Which contrary to popular opinion, Cryptic loves selling; they can do more with all your cash up front in development terms, and C-store sales will keep the lights on later.)
That doesn't mean that when 1,500 days comes along they won't decide to give us a little thanks; it just means they're not planning for it right now.