Finn Balor appears to be Brock Lesnar’s most likely opponent at the Royal Rumble as of now, according to Dave Meltzer in the Wrestling Observer Newsletter.
Lesnar’s mostly meaningless match with Jinder Mahal at Survivor Series will basically just be something for him to do as WWE tries to pass time until Lesnar’s eventual match against Roman Reigns at WrestleMania 34, where Reigns is expected to win the Universal Championship.
Reigns seems like he will still be involved with The Shield in some form by the Royal Rumble, so Finn Balor will likely be the next person to feud with Lesnar. Balor had been planned as a possible feud for Lesnar earlier this year, but WWE changed those plans after a couple of injuries forced them to reshuffle things. Seth Rollins had also been planned as a possible feud for Lesnar, but he is now involved in the tag team division and The Shield. WWE has been teasing a Balor vs. Lesnar match for a while, with Balor constantly saying that he is going to come for the Universal Championship ever since he returned from injury.