Radio telescopes are hilariously massive. I'm not sure it'd be easy to reproduce their capabilities in space?
Right now for the price of that one project one could have a humongous radio telescope in orbit without any interference. If only people could really look forward.
Radioastron required cross-correlating the signal with ground-based radio teleacopes in order to do science. The collecting area, dish distributons, etc. would need to be fully replicated in space if one wanted to avoid using ground-based facilities entirely.
Now we can launch two. Or two dozen. This completely obviates any need for ground listeners as for resulting angular resolution.
Since ground-based radioastronomy has other uses, will stay there anyway and since crosscheck is always better, future long-base radiointerferometry will use legacy ground-based observatories.