I think we should assume that in the near future after the series Bajor joined the Federation. Remember that they were very close to joining the Federation, and the only reason they didn't is because of Sisko's brain disease prophecy, and the only reason for the brain disease prophecy is that if Bajor had joined the Federation at that point the !!!LOCUSTS!!! would have been a lot meaner in the occupation arc.
Actually, it would have ben cool if in Voyager one of the letters from home talked about Bajor joining the Federation so the Bajoran members of the crew could react. I wonder why they didn't do anything like that.