My full headcanon on future Cross Guild pirates.
Reasons:
- return fan favorite characters which are all connected in some way to Cross Guild
- return said characters with fitting character arcs (Mr 2 + Mr 3 + Crocodile, Mihawk -> Perona -> Moria)
- make it strong enough against Blackbeard so Zoro still fightes Mihawk after Shiryu.
Even if Mihawk is Yonko tier, alone he can't be a shadow Yonko with Buggy, so he need a strong crew with him, something more compareable to Kaido/BM/BB/Luffy, which can be done with Marco, Vista, Mr 2, Moria, Page One and Ulti.
weakest crew but with a very strong shadow Yonko + the potential of stronger Crocodile and Buggy with awakenings.
Possible new characters to join: the none existing king of bounty hunters
Random lvl 6 prisoners that didn't join BB that Oda will retcon into Buggy
edit:
Doflamingo can come here, especially if Page One + Ulti end up here instead of forgotten/going on a cover story unrelated arc because they were both Beast Pirates. this adds a stronger connection with Mihawk, Crocodile, Moria, Buggy, Marco, Vista, all whom were Shichibukai together or in Marineford. I don't see how I'll serve even in joke under buggy, or allow himself to sit at the same table as Mihawk and Crocodile, unless once again he changes and gets a character arcs and gets humbled or something
I see him as a random ally in the final war like how Crocodile was in Marineford
