There's no ETA on when we'll start seeing it, but Dolby says that it's doable, maybe even without height speakers.
If you've had a chance to hear Dolby Atmos then you may have the same question as Dolby does – how soon can Atmos be in home theaters? Dolby says that they're actively working on adapting the tech to existing home theater setups and that they may even be able to get away with Atmos on home theaters that lack height channels.
It's not just 7.1 channel setups that Dolby is looking at either. They're checking out 5.1, 2.1 and even home theaters that use soundbars in order to find out if they can include a version of Atmos. The technology apparently scales very well, so expect to see something along those lines on home theater products before too long. Unfortunately, the "when" of it is a mystery as Dolby doesn't have any time estimates.