This is the third show in a row that he's coming down from the ramp. I'm starting to think that they're getting ready to finally turn him heel.
Reigns is coming down from the ramp because they are scared of what fans might do to him. He's not turning heel, at least not yet.
Not saying that you're definitively wrong (because you could be right), but I have a hard time seeing them change his entrance because of fear for what the crowd might do. He's done his usual entrances with hostile crowds before (even at the RR and WM last year).