Mcgregor vs Aldo
Mcgregorvs Alvarez
Either of those two actually changes the UFC, the others does not change the game, it changes the respective division´s landscape but thats it, Aldo beats Mcgregor then he never gets the 145lbs belt, moves up to 155lbs anyway as he clearly wouldnt bother making weight 1-2 more times to get the title fight, he moves up but he doesnt get a title fight right away, nothing changes.
If Mcgregor beats Aldo but loses to Alvarez then there is no champ champ status, he wasnt returning to FW anyway, no Mayweather fight, no FW title to fall back on, he wasnt going to bother making 145lbs again, he looked like death doing it.