UFC is as desperate for publicity as WWE is, that's why they went all out in trying to get Georges St Pierre to come back to the UFC. They are losing money right now because of how much the new owners paid to buy the company so i wouldn't be surprise if they except to send Jon Jones to summerslam the same way WWE let Lesnar go to UFC last year.
While this move would benefit both company, UFC kinda owed WWE for letting Lesnar fight last year and this would probably settle that debt. Plus it would get people talking about this bout which quite frankly, i don't see happening unless they can find a way to convince an athletic commission to sanction a fight with fighters from 2 different weight class. But at less it's good publicity for WWE because they get a celebrity from the UFC world and it's good for UFC because they get more exposure from him being at summerslam and maybe even WWE plugin the Next UFC PPV on summerslam. So it's a win-win for both company.