In regards to Brock turning baby face, I'd rather they not go there. I guess they'd like to explore it some before Brock's contract runs out at Wrestlemania 31, though (assuming he doesn't sign an extension.)
Anyway, I had the feeling that Ryback/Lesnar could possibly occur at some undetermined point in the future after seeing the Ryback/Heyman pairing. Partnering up with Heyman means Ryback is one step away from sharing screen time with Brock, and I can't resist feeling that the 'E may have them meet up at some point. The match would have that Big Man aspect to it that WWE likes. I also pondered this match being a slight possibility for Wrestlemania 29 if they really wanted to get Ryback over. He could have been the reason Punk retained at Hell In A Cell last year (Heyman is afraid of Ryback destroying Punk for the belt, and so he calls upon Brock to help), which could have been the catalyst to build towards Brock/Ryback for Mania. Didn't happen, of course.
If they are really intent on turning Brock face after Mania next year and the Ryback/Heyman affiliation is a success, then they could always go at it at Summerslam 2014 with the back story being that Heyman has found a new and improved monster to watch his back in Ryback, who he has target and attempt to destroy Lesnar.