This seems roughly right, but out of curiosity I wonder what the results would be like per-developer rather than per-app, if those numbers are possible to come by.

It's plausible that these numbers mean what the article interprets them to mean, that a long tail of developers is getting a larger share of the revenue than previously. But, as-is, these graphs don't exclude the alternate explanation that the "rich" people/companies, so to speak, are still pulling in most of the revenue, but by switching to a many-small-apps strategy.