The Becky Lynch/Cris Cyborg back-and-forth on Twitter seems to be leading to something that has the blessing of WWE. Cyborg has been pushing for a match with Lynch at SummerSlam. I don't know if the match will happen but sources close to Cyborg's camp have indicated that they have come to an agreement with WWE. I reached out to WWE over the weekend and there was no response from their side.
Cyborg and WWE have talked in the past and she is currently under contract to UFC so that is a hurdle that she would jump through. However, as noted in the Wrestling Observer newsletter, UFC does owe WWE because Brock Lesnar was allowed to fight last year while under WWE contract.
Cyborg has had a rocky relationship with UFC but she recently made up with UFC head honcho Dana White. She will fight Tonya Evinger for the vacant women's featherweight championship on 7/29 at UFC 214. I don't know if this will happen but if there really is a deal in place for a match with Lynch, then her UFC 214 post-fight interview (if she wins) could be the right place to officially start the angle with Lynch by formally announcing her plans to try her hand at pro wrestling and laying down the SummerSlam challenge.