This is something I was really wondering about with RDA. Conor is used to fighting shorter orthodox fighters and his greatest weapon, his left hand, is opened up with the southpaw/orthodox matchup. Of all the conor fights i've seen he hasn't been in there with many skilled southpaws. With as well schooled as he is i'm sure he will have a plan and im still expecting him to be the better striker, it isn't like his left hand will suddenly not work but he'll have to make some changes. Holloway fought the whole fight against Conor in orthodox despite being great from both stances himself.
Now he's fighting a southpaw who's longer than him. It's an interesting question. Nate looked good in his last fight against a southpaw. I think being a southpaw, esp in MMA can be kind of a big deal, or at least a factor. It changes the ranges and most guys aren't used to it. A lot of the champions are southpaws or fighters who can fight from both stances.
I think grappling wise, at least from the wrestling/takedown perspective. Mcgregor matches up well here. He has good balance in the clinch and Nate's takedown game is only clinch TDs. If Nate can make some scrambles I wouldn't be shocked at all for it to be over quick with a Diaz win but it isn't going to be easy.