Laverty and RDP would be obvious choices. I'm not sure RDP would be my choice but I can understand why they will want to keep him as he has been testing the bike and they will likely want some continuty in their first season.At the end of the day though it all comes down to sponsorship, who's available and how serious Suzuki are. It would be unlikely for them to attract a top flight rider and the necessary sponsorship if they choose the 'Open' route.
regardless of how you or I rate them some other possiblities could be.
Hopper- back racing (god knows how), seems to be able to attract sponsors and being American could help his chances.
Bautista-Did well for Suzuki in the past and I think he may be out of a ride next season. His seat likely going to Nakagami at Hondas request and cost. Again will probably come with a wedge of Spanish gold.
Redding- I can't see Honda stepping him up to a sattelite ride next year and the RCV is too asthmatic to give him much of a chance of a decent showing this year. Could be a good shout.
Dovi/Crutchlow- If Ducati don't sort it this year they will both be looking to jump ship. Yes, I know Cal isn't out of contract but he will likley have a performance clause allowing him or Ducati to break the contract at the end of the season. Either woud signal Suzuki are making a serious effort.
Last one before I get ripped into for talking speculative nonsense.
Real, real long shot here......
.Ben Spies. If Ben has managed to get his head straight and if he has managed to get himself fit he may just feel he has unfinished buisness in Motogp. If he did decide to make a comeback he should be able to attract decent sponsors from the American market and Dorna would welcome back as he should help maintain/raise the profile of Motogp in the USA. Not very likely I agree. His last two season in Motogp were painful to watch he really did seem broken when he left but I also feel we never actually saw the best of Spies.