I'm really enjoying having content so freely open to me, so I would not want to lose that even if I was paying a subscription. For example, I love having access to pretty much all of the costume pieces in game, the option to create Epic AT's right away with no level restrictions, the ability to easily choose my alignment from Null the Gull, prestige powers available right out of the gate, and so on.
Things I would like to see added would be:
1) New powersets
2) Balancing of existing powersets
3) New costume pieces
4) New story content
5) More levels beyond 50 or additions to the endgame systems
6) More epic archetypes that let us play as different hero/villain factions with perks like Skulls, Carnies, Knives of Artemis, and so on.