#1. The Fiend interferes and stops the match
The Fiend hasn't been seen or heard from in a quite a while now and one has to wonder if the company is saving him for some kind of surprise return at Backlash. Interestingly enough, The Miz and Morrison seemed to take digs at Bray Wyatt's Firefly Funhouse a few weeks ago, which could point to some kind of future encounter between the three.
How it happens though is probably going to be the most intriguing part of of all this and will no doubt set the tone for the title picture going forward. For example, the match at Backlash could be going on as normal when the arena goes dark. The Fiend then appears out of nowhere and chokes out Strowman with The mandible claw to get the disqualification.
Or WWE could do a past-coming-back-to-haunt Strowman again angle and make his opponents disappear with a flick of light. This would leave Strowman and The Fiend having a stare down in the ring and automatically leaves the door open to a fatal four way match at the next pay per view.