Conor proved in this fight he's an elite striker, even against a bigger opponent. However, bigger opponents are used to heavier hits to the head. He needs to just sit back and chill in his natural 145 division and reign supreme. There's nothing wrong with staying in your weight class and dominating, look at Jones, GSP, Silva, Ortiz, Hughes, Liddell. Especially in UFC it's hard to go up weight classes and succeed. One good example is when BJ Penn also went up to welterweight and was TKO'd by GSP.
The only reason he took this fight was because he was bored and there were no elite contenders in his own weight class who were available to fight.