Google could obtain a social network graph quickly from gmail accounts.
Moreover, it could release a platform similar to Facebook based on GWT but take it another step further by providing free hosting on its massive computer cluster.
There would be some sort of revenue sharing system in place for apps created using this platform.
Instead of hiring so many software engineers worldwide, Google could "outsource" much of their app development to entrepreneurs.
Although Google already acquires a few startups here and there, one would expect thousands of apps to be developed quickly in what I described above.