Star Wars: The Old Republic was always going to be hugely successful. It's a Star Wars game, it's a Bioware game and its a heavily marketed MMO. The question was never whether it'd be successful (unless you're talking about EA Louse), but how successful it would be.
That question has today been answered: very successful. At an investor conference yesterday, EA CEO John Riccitiello announced that, for the end of February, The Old Republic has 1.7 million subscribers. They hope to have beaten the two million mark by the end of June and hope to sustain that amount through to 2013.
The hit MMO has yet to launch in Asia, but will do so later this month and will likely boost subs quite a bit. The developers had said that they needed only 500,000 subscriptions to end up profitable, so a cool couple of million will be turning over a nice profit and perhaps even ensure that that plan to keep the game going for 20+ years could come to fruition.