Wow, procreation must kick into overdrive at that point because Satan is only loosed a short time!
It's not called Paradise for nuthin' ;^)
Actually, we don't know the length of the "short time".
Children have been being born for a thousand years. Not all of them come to a saving faith in Christ, I would even argue that the majority of them do not. Satan is loosed and those not believing in Jesus Christ knowingly throw their lot in with Satan, thus becoming tares.