The 30 year-old is rebuilding following a fifth round loss to Gennady Golovkin in September and could remain at 147 pounds despite strong links to a move up.
That being the case, a clash with the winner – who Brook is adamant will be Pacquiao – could be on the horizon.
“Of course I would be interested in the winner,” Brook told ESPN.
“All the fans were saying I didn’t fancy fighting the best fighters, but I have gone in there with the best in the world in Golovkin, and I’m ready to do it again.
“I’m after the biggest and best fights out there, those are the ones that are going to get me up for it.
“Once you have become world champion, you need special fights to really keep you motivated in training. A world title unification fight would do that.”
On the Pacquiao v Vargas fight itself, Brook added: “I see Vargas getting some success, but I just think with Pacquiao’s experience, having been in with the better opponents, he’s going to have too much.
“But I don’t see Pacquiao stopping him — he’ll win on points. He’s had a lot of time out: is his passion still there? It could catch up with you at that age, so he’s got to be careful, and that makes the fight interesting.
“Vargas is a good fighter — he’s a world champion — but he’s not the best out there. There’s not massive margins at this level, but I don’t think he’s in the super league with the likes of Keith Thurman, Danny Garcia and myself.
“Unless he shows us something I’ve not see before, I don’t see him winning,” he said.
