What I think is happening is that the best people tend to leave, and those who prefer safety and are fine with the corporate environment as long as they're getting paid tend to stay or join. I doubt this downward spiral to mediocrity can be reversed.
I actually can't decide what would be the best strategy from the CEO's point of view. I.e. how best to govern an aging, established tech company like Google? I really like what Aswath Damodaran said about Google - there's a "sugar daddy effect" - the various departments lack desperation to make it, unlike startups.