I always found it rather odd that producers rarely disclose ETAs.
At first I thought it was because of the customer base - the company thinks it loses a lot of goodwill if it can't live up to its "promised release date".
But I guess it's more likely that schedules change so frequently that there's little point in releasing a date until it's near-certain.
I would be very surprised if it arrived as early as march. 1.2 is next, and then they can start on the expansion.
From what frogboy has said, the full elemental team will stay working on elemental for 2011 and some of 2012. That would put at the very least 4 months between each expansion, which would mean we'll see the first expansion earliest april, possibly may or june.