IMHO Seth Rollins is absolutely not ready to wear the big gold. However, I'm down with him as Mr. MITB. He now has around a year to evolve, get into the main event picture and show off is talent.
I'd still love to see Brock as a champion (on a heavier schedule) defending it against Roman Reigns at WM31. That gives Seth some interesting options to cash in afterwards.
But - honestly - I don't believe that WWE will wait that long until a cash in. Having this in mind there is a valid chance, that Seth might cash in and lose. If this is for the greater good of a huge storyline, I'm down with it. Else, he really needs to gain some more authenticity. I'm not saying he is bad, but I don't see him as a main event player at the moment. He would make a perfect IC champion, but not HWC.
I never was a fan of putting the title on somebody just because he is a talented wrestler (e.g. Swagger, Ziggler, Miz). That takes prestige from the title and doesn't really help the title holder (how relevant is Swgger, Ziggler, Miz right now?).
Seth is an attraction now. We'll see if and how he handles it to be "championship material". Could be a really interesting summer!