It's possible but I always err on the pessimistic side with Roger, that way I'm always wowed. He needs 6 titles to actually overtake Lendl but there are only three tournaments you would say he is the out and out favourite to win from the start: Stuttgart, Halle and Basel. Even at the first two there are chances he could be upset by Zverev (Alexander), Goffin, Thiem, people like that. So then, assuming he wins those three, he has a chance to win any of Dubai, IW, Wimbledon, Rogers Cup, US Open, Shanghai, Paris (if he entered) Cincinnati, WTF. These are less likely and much more difficult to win.
So it's entirely possible but I would expect him to finish more around the 92 mark.
Goffin or Thiem upset him on grass?
He can be upset by big hitters with big serves on grass, as almost all his loses on the surface suggest (Raonic, Tsonga, the Stakhovsky incident). Without considering Nole or Andy, they obviously can upset him.