PvP is endgame. I started when F2P came out. Got all my endgame gear (multiples for multiple ships) in about 4 months. PvP has kept me playing and now Im part of the community, in a fleet, made new friends.
I'm a relatively new player, but in the course of a few months I have completely leveled up 3 separate characters and am very to fairly proficient at completing all the elite stf's. For a 3 year old game it certainly doesn't offer much in the way of engaging pve content and considering CBS probably has very tight constraints on the star trek IP I somewhat doubt there will ever be continually progressing pve content and judging from what I've seen so far I'm not sure Cryptic has the AI and story writing talent to make engaging pve content and bosses like other MMO's have.
In short, I believe the future of this game lies in its pvp and fostering the pvp community. I'm a lifelong pve player who has always been intimidated by facing the "pvp kiddies" until recently, I've finally had my arm twisted enough to jump in and now I realize it's actually fun and the pvp community here is actually quite kind, respectful and helpful. I know now it's the pvp that will keep me playing this game for years, not the pve content.