Modric is not a scorer like those two, so it Is not clear indicator on how he plays, but basically if he doesn't get injured and plays almost all games then yeah he will be good. They can pay him 100+ million a year, he would be famous enough to do that, but at the same time it wouldn't be easy to convince him neither. Just because he is there, doesn't mean that he would be willing to play, that Is why it is a risky move to pay that much to him.
If modric is in a team that has players willing to play, he also is going to be willing to play. Modric in a team that has Ronaldo and all the players that Al-Nassr FC has will make Modric to be willing to play because he'll be getting the motivation to win trophies. Ronaldo changed the mentality of the Al nassr players but Benzema thinks he came for vacation and he's only enjoying himself while the team is doing all the work, this is why he has being playing badly. Ronaldo teams has Sadio mane and others always trying to win every single game therefore modric should be very selective of the teams that he'll be going to join or he'll end up becoming a bad footballer as Benzema is becoming. Saudi leagues isn't competitive to the standard of trying to be a solo player, you need everyone in the team to have an impact on matches and winning them.