Both Google ( GOOG) and Amazon.com ( AMZN) have found a way to build their own device ecosystems by building dominant public clouds. It's the cloud that is the platform of the coming decade. What should be most disquieting is that both Amazon and Google have used open source to create these ecosystems and these dominant public clouds. What is the lesson? Open source, by itself, is no guarantee of market competition. We want market competition -- the more of it we can get, the more investments we can create, the more growth we get. But something beyond mere "open source" must exist to assure that competition continues. In a healthy tech economy, there are a lot of winners, and in 2012 there are just a few. At the time of publication, Blankenhorn was long IBM, MSFT, AMZN, GOOG and AAPL. This article is commentary by an independent contributor, separate from TheStreet's regular news coverage.