A permanent, secular rise in the maturity of the tech startup ecosystem (and of "software eating everything") would exhibit many of the same signs of high growth, or the same collection of Verhulst growth curves in disparate indicators, as a bubble. Dev salaries, SoMa rents, and MBA hanger-on density are probably useless in distinguishing between the two.
Sure. Growth in value, as measured in users plus at least one of profits or strategic value. I see Tesla, SpaceX, Twitter, and Github and I do not see a bubble. Instagram and Tumblr are good examples of growth in strategic value being enough.
I don't actually see the separate and distinct economic value creation in Instagram, Twitter, or Tumblr, nor do I see the economic value capture in Github.
The economic value of GitHub is in making team collaboration and communication, the primary bottleneck in team development, that much more efficient. That is hugely valuable, as it increases the economic productivity of companies writing software, and allows teams to organically form (and dissolve) without much organizational overhead. It is a huge improvement from the days before SCMs (let alone SCM-based project management cloud-software), and even a large improvement over the days of CVS, SubVersion, and SourceForge.
