[MarchHare]

If BioWare wants to make another ME game, that lends credence to the idea that there will be a new ending available via DLC.

ME3 spoilers and speculation about future sequels below:

Spoiler!

Given that the game ends with the Mass Effect relays destroyed, it would be pretty boring to have another game in this setting now that effective travel between populated systems is impossible.

What they should have done is give us the ending we wanted -- Shepherd defeats the Reapers (potentially at the cost of his/her life and that of most/all of the crew), the galaxy suffers great damage during the war, but it is left in a state where it can be rebuilt in a few years or at most a decade or two.

Instant sequel hook: BioWare could then continue the series with a new protagonist and crew having to undo everything Shepherd did during the Reaper war. You cured the genophage? Well guess what, the Salarian ambassador was right, and now the Krogans are rampaging across the galaxy again. Ditto for the Rachni you saved. And you also upgraded the Geth with Reaper code? Guess how that's going to work out in the long run...