It'll be interesting to see what happens at TLC because typically TLC isn't considered a top PPV and I don't think they'll do a Brock Lesnar John Cena title match for it, but if it doesn't happen then who knows the next time we'll see Lesnar in a title match.
Royal Rumble was originally marketed as a 40 man royal rumble match, but it got changed back to a normal 30 man match and John Cena is being advertised as one of the 30 men. If that's true, I don't think he'd also have a match against Lesnar that night. Because Cena beat Orton in the steel cage match for the shot to wrestle Lesnar again, wouldn't it have to happen soon since the winner of the royal rumble gets the number 1 contender spot to headline Wrestlemania and they'd probably start pushing that feud right after the rumble?