That opens up a realm for a thousand and one possibilities, not all good. The tech level for the majority of the world is rather low (or completely underwater). The ability to spelljam is really advanced.
However, if you make the city old and decrebed in the ass end of Spelljammer Space, so there is erally no reason (good or bad) to get out her that might work. Basically, they would be trying to fix their city but so much is destroyed or just being held together with duct tape no one sane wants to go there.