No one has confirmed anything to us but someone close to the people involved hinted to us that McGregor could end up in a storyline with WWE at some point. I wouldn't rule out the beginning of a storyline at SummerSlam on 8/21 with the conclusion at WrestleMania in Orlando. I guess it would all depend on the outcome with his fight with Nate Diaz on 8/20. McGregor followed the McMahons and Becky Lynch during WrestleMania weekend and we hear that McGregor's camp is absolutely open to the idea of working with WWE at some point. In the past, his UFC deal would have prevented him from working with WWE but the deal with Brock Lesnar may have opened some doors. Also, keep in mind that Sheamus has done promos in the past at live events and they've gotten into at least one twitter exchange. None of that would have happened without WWE's approval. Last year, Sheamus told The Irish Mirror that he would fight McGregor if he had to. He said, "Would I take him (if I had to)? Absolutely. Course I would. No one could take me. No one’s better than me. I could walk over anyone."
I also wouldn't rule out the possibility of a deal being made for UFC to promote SummerSlam during UFC 202. UFC 202 is expected to draw a huge buyrate because it will be headlined by McGregor vs. Nate Diaz. WWE had a working relationship in 1997 when they signed Ken Shamrock. In fact, they plugged UFC 13 on Raw and on their syndicated programming.
UFC is hoping to get Ronda Rousey back later this year but she recently had her knee scoped so don't expect to see Rousey doing anything physical in UFC or WWE until the end of the year, at the very least. Also, her movie schedule may keep her away from WWE. She is set to film Tina Fey's "Do Nothing Bitches" film sometime this year or early next year so WWE's best bet, if UFC allows it, would be to get McGregor.
Here is the twitter exchange between McGregor and Sheamus from a couple of years ago and scroll down further to see Sheamus' promo on McGregor at a show in Dublin, Ireland last year: