I predict Android will enjoy a period of dominance that will be remarkably the same as Windows. Android will dominate mobile devices, plus a few other areas like maybe cars, appliances, TVs, some wearables, and the random embedded things that used to run Windows CE and Windows Embedded, very much in the way Windows dominates PCs. Probably, like Windows, for decades.
The question is whether that will matter the way Windows mattered to computing. I would have expected, for example, a lot more people who write software for the enterprise to start making tablet apps. They're not. I don't know if this is a wave that is late coming in, or if vendors think touch Web apps will be good enough (which they are not, for anything that is popular in an app store), or if that kind of dominance just doesn't matter as much anymore.
Android is a pretty sweet tablet OS, and I could see there being a lot more of it where PCs are serving as office productivity nodes. Tablets have the potential to to change the workplace for the better: Users not tied to heavy PCs or laptops in cubicle workspaces, etc. But it's slow to take off.