Here are my two cents on the RR match.
With Roman Reigns going #1, I think Brock Lesnar will go #2. I also think it will end with those two ending the RR match. With there feud history and how Raw ended last week with those two brawling, I could see them both starting the RR. Then you have them brawl during the RR match, of course taking out others as more come along with those two only in the ring for a while brawling ( say Bryan Wyatt comes in and then the ring fills up ).
2 options, if not 3. One would be Roman Reigns wins the rumble match ( outside interference maybe ? ). The other option would be the help of HHH helping Roman Reigns win the rumble match ( heel turn of course ). No one would guess that and, I think it would help escalate the feud ( even story ) to WM but with a pure heel vs a lovable face. Because at this point the two are basically looked at as two faces in the WWE.
Other option would be, having Daniel Bryan ( yes I'm still sticking to that lol ) win the RR and the title. I could see Roman Reigns being eliminated half way during the RR match ( say around #16 with the cost of HHH's help ). I think doing that would obviously give the hint of HHH vs Roman Reigns at WM, but eliminating him that early , no would expect and give the RR match more hope and potential as to whom the next champion could be. Because at this point Roman Reigns going at #1 is pretty predictable at this point knowing hes either going to win or come down to the last 2 in the match. Then of course with that option, the RR match would end with Brock Lesnar and Daniel Bryan with Daniel Bryan winning the match and the title and, hopefully a feud going into WM 32 giving us a potential David vs Goliath match
I realized that none of this will come true but, I've clearly had to much time to think about this lol.