None of these continue the development pattern of the crew. Ussop got focused development in Dressrosa. He inched closer to his goal. There was a whole narrative surrounding it. Sanji not only got development, it was packaged with his backstory that was presented in a Yonko arc. Zoro is currently getting focus in that same vein. There might or might not be a connection between those that started his village and Wano. Even if you eliminate that and it's not anything deep, he is getting development as a VC. It has been done subtly and direct at times. Zoro being the one that reminds the crew what is at stake or the circumstance/reality of the situation. While Luffy is locked up, he keeps getting tangled into his own journey through this country from the history with Ryuuma, to the people of Ebisu Town, etc.
Are we sure that this doesn't continue. I don't see this in including in your speculation of the 4 arcs. The others kind of skipped over it as well
Nami's skills will be put to the test in mapping the voyage to Laugh Tale; more importantly, her dream of mapping the entire world may not be realizable at the present moment. What if this isn't the way the world is meant to be? Maybe during the war, we'll find out about her home island. Nami has a heart for those affected by war. She's got a soft spot for children. The story with Mocha and the Punk Hazard kids victimized by Caesar relates directly to both her and Chopper.
Usopp will most likely get a lot of focus during Elbaf; He has always had strong connection to the giants and his dream of becoming a 'brave warrior of the sea' would be furthered by fulfilling another of his false boasts to Kaya about an army of 8,000 followers.
Chopper - see Nami re the Punk Hazard kids. As for his dream? Maybe he cures the illness that killed Roger? My friend has a theory about Laugh Tale making sick anyone who possesses a devil fruit power. Buggy and Toki both became ill as they approached Laugh Tale. No one on Roger's crew who reached Laugh Tale is known to have a Devil Fruit ability. Roger, Rayleigh, Crocus, and Oden definitely do not have DF abilities. Maybe he finds a way to facilitate this journey for himself, Luffy, Robin, and Brook. Maybe Chopper visits the Cherry Blossom Island that 'cured' Hiruluk? Maybe it's the same place Roger and Whitebeard shared a drink.
Robin - I could see her easily getting a lot of focus in three of those arcs; The Revs, who already have a relationship with Robin, could be part of a Vegapunk arc. She could be a target for Teach, seeking to reach Laugh Tale. And of course she's the only one who can relay the truth of the Void Century on Laugh Tale. Not to mention, she's likely the only one who can discern the location of the ancient weapons. Also, we still don't know about her father. Olvia was 'fulfilling her husband's desire' when she set out to research the Poneglyphs. I imagine this will be explained.
Franky - has deep connections to Vegapunk. Maybe his asshole pirate parents are part of the underworld connected to the SSG and Marines. His speech as they departed for Fishman Island about Kuma also foreshadows a future storyline. Maybe we find out more about Franky's parents.
Brook - Whenever they see Laboon again, he will enter the spotlight. His country of origin hasn't been named yet. He was the captain of the royal guard before joining the Rumbar Pirates. Maybe during the war, we find out about Brook's nation of origin and learn more about his past.
Again, this is all speculation - but I'm not quite sure why arcs focused on those particular things would somehow preclude development for the Straw Hats. Even if I'm dead wrong about all of this, the Straw Hats development takes place organically as part of a larger story arc. Wano isn't a 'Zoro arc', but Zoro plays a bigger role potentially than other members of the crew.