Royce has had a very long ranging effect indeed. Right now, we can see that McGregor has influenced fighters to demand more and to try and push for money fights in the relative short run. He's one of the best striker sin MMA right now, but he hasn't changed the way anyone is training or anything like that, which Royce certainly did.
Royce's skillset of BJJ or at least the ability to defend against that skillset is bread and butter for almost every MMA fighter. McGregor is a shooting star and won't have much long term influence imo.