The obvious solution is antitrust law. Why is Microsoft no longer the competitive boogeyman of the 90s? Because it was prosecuted under section 2 of the Sherman Act in 1998 [1]. Everyone would be using Bing, Zune and Internet Explorer otherwise.
But the last two administrations haven't prosecuted anyone under section 2. Just imagine spinning off Gmail, Google Maps, Chrome etc. and letting them survive on their own merits.
[1] https://en.wikipedia.org/wiki/United_States_v._Microsoft_Cor...