Once Greg has done this show, which I suspect will be within the two years (as Chris Moyles said in a Podcast a couple of years ago, nobody will ever beat his record of 8 and a half years, they'll be too old and untrendy long before then) much like Moyles, he'll leave the station. However, I think he will stay at the company barring some huge offer coming in from Commercial Stations (could only see it being Global), can very much see his future at the BBC at either Radio 4 or 5 Live. I think it's very likely we see him on Test Match Special at some point, the perfect sort of guy for it in the future.
Scott will be off within a couple of years too I predict, which will obviously be sad and the true ending of a huge era at the station, but he will almost certainly end up on Radio 2 daytime, and could see him doing more Radio 5 Live stuff possibly too in the future.
Jordan will absolutely take the next Breakfast Show gig, but almost certainly with someone else, either Katie or Vick, and I suspect the other one that doesn't take Breakfast will take Drivetime. Once Scott leaves, Dean will probably get his slot or they could move RMC to his slot and put Dean in the Live Lounge slot. For me, the evening shows seem set for a while, considering there's a whole new schedule coming to that especially around weekends from September.