Expanse was apparently axed at end of s6 because of budget reasons from one Reddit comment thread I came across a few years ago, someone quoted something along

Expanse was apparently axed at end of s6 because of budget reasons from one Reddit comment thread I came across a few years ago, someone quoted something along the lines of "Internally it was called 'The Expense" because of how much the show cost to make". Makes you wonder if someone else would be willing to put up the money for new stuff. But then again you have shows that cost multiple millions per episode these days. A small hope of something is better than nothing.