Roman wins clean, Dean plays mind games - Possible.
Seth wins clean, Dean plays mind games - Don't think Reigns' situation could have affected this scenario. Ambrose was probably meant to cash in on Rollins anyway.
Roman wins clean, Dean cashes in - Don't think they would've had a 3rd cash in on Reigns in just 14 months.
Seth wins clean, Dean cashes in - Funnily, what actually happened might have been the plan all along.
Dean wasn't supposed to win MITB and Roman was supposed to retain Improbable. The RAW Shield segment had pretty much foreshadowed Ambrose winning the briefcase.
All in all, if I had to put my money.. I'd say Reigns was probably supposed to be a lot more protected in his loss than he was, with Ambrose cashing in regardless. Still, should wait for more concrete reports about when did the incident occur. It feels strange that they set the ball rolling for the Battleground match and then suspended him when they could have sold a kayfabe injury or something until Battleground. I think this incident has to be post RAW.