* the Times employed Krugman to generate content, originally on terms that included a Times-branded blog where he could write with minimal editorial oversight.
* The Times consolidated their opinion content and eliminated the blog, leaving Krugman only venues with extensive editorial oversight, notably including how often he wrote about specific subjects (that is: with an editorial calendar).
* He started a Substack; the Times freaked out; he ended up leaving.
This feels like a lot of Substacker stories. He will probably have a bigger and more lucrative audience on Substack, and the Times probably won't suffer much from his departure.
From my own vantage point, the less the Times can index on punditry, the better. I don't pretend this change is strategic for them, but I think it'll probably work out to their benefit so long as they don't immediately go hire another economist.