For now this is just a rumor and not even a good one at that.
Rumors are now circling that two previous GTA radio hosts are working on a game at Rockstar. That is the rumor.
Now onto the speculation. Reports from Sirius XM revealed that two of the DJs that have appeared on that station are now currently working in the same studios that recorded the tracks for a previous GTA game. Well, For starters, we know that Chuck D from Public Enemy was on the list that appeared in GTA 3 which took place in the same area where V is supposed to take place. Chuck D is also a DJ on Sirius. Not too sure about who the other person will be but knowing Rockstar, they will probably get another big name. Personally, I don’t think that Howard Stern will be on it but it might make sense that they will get someone a little more quirky that will be nostalgic and unique. My money is on that they will include George Takei from Star Trek fame to host one of the radio stations because his voice is amazing on radio (hear him on Howard Stern from time to time) and if you put him in a GTA game, even better.
So current fake speculation is George Takei and Chuck D. Probably true.