The words "space economy" covers a huge diversity of possibilities. Even asteroid mining is a space economy. Space-based solar power, to some extent. So, a "space economy" can cover everything from asteroid mining to something like Iain M. Banks' Culture series.

How it pans out will depend on any number of things. Whether we have FTL travel. How good automation gets. And frankly we barely understand the economy here on earth. Even economists were (and are) all over the map on predictions, for COVID-19 ramifications, looming decline of fossil fuel demand, declining fertility rates, etc.