So there’s been three groups with a decent bit of focus since Wano was over
Red Hairs
Cross Guild
The RA
Also the Marines, but the Marines are a bit of an ever presence and there’s pretty much always a good chance they’ll get involved in an arc.
Shanks is linked to Luffy, and in Cross Guild Mihawk and Buggy. He’s going after Barty, one of the GF. The GF are meant to cause a massive incident. Two were at the Reverie, and Hajrudin dreams of being the King of the Giants so should be involved in Elbaf. Yasopp and Usopp also obviously linked, with Usopp having ties to Elbaf as well
Cross Guild. Mihawk linked to Zoro and Shanks. Buggy to Shanks, the original three Strawhats and the ID escapees (Including Ivankov and Inazuma in the RA). Croc, Luffy and Robin in the Strawhats and a mysterious past with Iva. Plus Vivi, who is pretty likely to be with Sabo
The RA. A good few links to the Strawhats. Family (Luffy, Dragon, Sabo), Robin was basically a member, Sanji was trained by Iva, Jinbei knows Koala, the pre-skip Strawhats owe Kuma. Vivi’s probably with them.
I think the next arc (or groups of arcs) will focus on these three, all culimating in Elbaf, where I think Vegapunk is experimenting on gigantification for the Marine Giant squad. The RA will want Kuma to be restored to his best.
Also, the cover story, reuniting the MADS group of Judge and Caeser, could lead them there as well.
Big missing factor from the end of the arc has been Blackbeard. Doesn’t seem he’s made his move yet.