New, final G4 form, with us also seeing the past forms as well. Boundman's been around a long time now- over five years now. Think it's clear that Oda is moving on from it and it's limitations, that's why Luffy's now using it against actual fodder instead of into being his trump card. There's something new to be seen. A "Perfect" form that combines every other form and his Haki use? I do like Tigerman as a name, but I can't recall Luffy ever using Tiger-themed attacks before.
Awakening will most likely be saved for Vegapunk to fully explain, we might see the first glimpses of it, but Luffy shouldn't be able to control it yet. His focus has been on Haki so far, after all.
Gear 5 will come, that can be a really hype moment for Blackbeard or something.
I've always wondered if Oda would give Luffy a Reverse Gear where he can't stretch in exchange for sheer power. Turning into something like a rubber bullet- I'm no scientist, but then neither is he. Say it's something like improved tautness and tensile strength? Think it would be really cool after years of Luffy getting bigger and faster to have a super powerful final form where he's right back to looking like his base.