If the game reopened, I'd be back on. I have plans to enact, minions to bully, heroes to sneer at, and worlds to conquer!
That said, I wouldn't return without a hefty cinderblock of skepticism on my shoulder. NCsoft would have to do a lot, and I do mean a lot to convince me that their change of opinion is sincere. Still, I'd give them the opportunity to convince me, at least.
I'm mostly with VV on this - they'd have to make sincere efforts to put Paragon Studios back together and provide them with a buyout option in the contract, should a shutdown ever be announced in the future. I would also insist upon plain and forthright communication as to why the change of heart occurred. I don't have a lot of faith in humanity ('cept for you guys here at Titan; you're alright in my book), and before I'd deign to spend any money on the resurrected game, I'd have to know that my purchase would have lasting value. I'd have to be convinced beyond a shadow of a doubt that the game hasn't just been reopened only to be shut down again a month or three later.