Google buys a webmail service, forces rapid improvements in the competition.
Google builds a browser, forces rapid improvements in the competition (Firefox).
Google buys a smartphone OS, competition already doing ok but probably tweaked some things.
Google starts building an inexpensive fiber network, makes incumbents sweat a little.
Google buys a smartphone manufacturer, forces competition to improve.
Next up, probably a mobile telco provider.
Google's thing seems to be improving the transfer and display of ads. Somehow they've turned that into a benefit to technology as a whole. It's a business model built on disruption.
Android played a huge role in pushing the mobile web to consumers. How long was the iPhone exclusive to AT&T, like 3 years? Without Android all those other wireless providers would be hawking much less functional Blackberries, Windows 6.x, Nokia handsets.
That said, my guess is that for the average consumer, things like that are far less important than having lots of easy to get apps, and a general look and feel that work well.
And I have to say that from that point of view, my cheap Samsung Android phone is just night and day ahead of the Nokia with Symbian that I had. The Nokia had Google Maps, Gmail, and some other stuff, but it was extremely clunky in comparison.
In mobile OS, I think they can avoid being classified having 70% or anywhere near it since Android is technically open source and anyone can fork it, and several flavors such as the kindle version of Android aren't under their control.
In the carrier space, they'd be far from owning a lot of market share.
They just need to make sure that if they acquire such power that they restrain from anticompetitive practices afforded to them by their position.
http://www.exeloo.com/ is the company that makes them.
Under some conditions (good visibility, easy-to-see lane markers, etc.)