I can't see Rossi teamed with anyone that would attempt to draw the spotlight off him. Not that Rossi is a media hound...but he knows the value of maintaining his "image", it's a lot more than just championships that has gotten Rossi where he is. He won't tolerate someone on his own team sharing that spotlight...he's too smart and knows he doesn't have to put up with that. Edwards was his dream team....a guy that really knows the game and really knows race bikes but just wants the job. I have no doubt that Edwards would move over and let Rossi by if a championship depended on it. Edwards has already shown his willingness to hold off hard chargers as long as possible when he's behind Rossi.
Remember...if Rossi started his own team...money would not be an issue, the guy brings millions and millions of dollars of sponsorship to whatever team he goes to. It's not a one sided thing...it's not all Yamaha paying Rossi, when a top rider signs with a team part of the deal is the sponsors that the rider brings with him, whether it be tires, helmets, leathers, etc it's cash the manufacturer doesn't have to come up with to support the team. The manufacturer typically pays the rider salary and provides the bikes, often the rider is expected to bring on board his own sponsors for much of the ancillary costs of the team.
Big time sponsors could care less who is making the motorcycles, they care about the rider....just like big time stars in other sports... nike didn't care who Jordon played for, they cared about who Jordon is. If Rossi went to Kawasaki the sponsors would still be there because of the attention he would get regardless of what bike he rides.
Edwards best move now would be to stay with Yamaha if they will pay what he wants for his testing expertise...or to go to a series where he has a chance of winning. His chances are non-existant of winning a championship or being a force in MotoGP (although being in the top ten every year is still impressive). And to be honest I don't think he has what it takes to be a force in WSBK....maybe AMA superbike. Problem there is the Suzuki's have been so clearly dominate in the series that if he wasn't riding for them he wouldn't see the podium much either.