I honestly think we will only see Elbaf after Wano and before Raftel. And maybe some chapters devoted to figuring out the island the Road Poneglyphs point to and tying together the way to Raftel.
Look at it by way of how many chapters this thing will last. There are reasons to believe that Wano will be more than 100 chapters plus the ending of the Reverie and all that stuff. I think there's a strong possibility that Wano/Reverie will be done at about 1040/1050. Than we have Elbaf. I mean, how long should Oda do this? It's a location the crew has to visit, so ~20 chapters at least, though more likely about 45/50, the length of Punk Hazard. Then we would be almost at 1100. Raftel and the Final War not considered into it. Keep in mind that when Oda had his first assumption regarding One Piece's length, he thought 1 Year east Blue, 3 years journey, 1 year Final War. Even in his most primitive state of the author's planning, he thought the Final War to be one fifth of the entire series. So I think 200 chapters seems legit for the Final War. And we have Raftel, which you can bet on a long True History flashback, some discovery and so on, so assume at least 50 chapters for this too.
In a nutshell, I think Oda has so much to do that he has a vested interst of not expanding the New World much forther. We already have a great To-Do-list.
Do I have a tunnel vision? Maybe. But I think given the authors habit regarding arc lengths and so on it's a reasonable estimation of how things will unfold and that simply leaves not much time. Oda literally has a great To-Do-list.
I'm not going to get into theoretical chapter counts, but for me there is a significant distinction to be made between what we, as fans, think/know that Oda wants to cover and what Oda himself knows that he wants to cover. I don't think anyone, myself included, can purport to have a full grasp of Oda's "checklist", so saying everything left can (to say nothing of will) be wrapped up in Elbaf->Raftel->Final War is a pretty bold assertion. Even if there are no other "major" arcs, I don't think a couple of smaller arcs (Punk Hazard or even Zou length) would necessarily be out of place, especially for plot points that don't necessarily weave into the big ones naturally. For example:
He can be introduced at the Reverie.
Setting aside the fact that I highly doubt we will be getting anything beyond exposition-dumps and flashbacks for what's left of the Reverie, we have no indication that Vegapunk is actually in Mary Geoise - last we heard, Smoker and Tashigi were making a fairly lengthy trip to get the Punk Hazard kids to him - and even if he were, the Strawhats are not (unless one counts Vivi).
Furthermore, the point isn't his introduction, but rather what role he will play going forward. There's his past connections to both Caesar Clown and Vinsmoke Judge, his role in the development of the Pacifistas (to say nothing of what he did to Kuma), and whatever he's cooked up to render the Shichibukai obsolete that may factor in. Even beyond his role as the World Government's inventor extraordinaire, there has long been suggestion that Vegapunk will answer many outstanding questions on the nature of Devil Fruits, which has the potential to tie directly in to Blackbeard's "power hunting" operations and how precisely that is being accomplished.
Whether he's really a threat that needs to be dealt with or not, I think there are pretty significant reasons for the Strawhats to meet him - and soon.
How about Elbaf? Seriously, Oda seems to like to create situations now, in which many plot points can be wrapped up pretty quickly, so why not "conveniently" having the last one appear where? Maybe with some adventure tied in to recover him.
The final Road Poneglyph is said to be "lost", so I'm doubtful that it can be found on Elbaf. More to the point, all the Road Poneglyphs thus far have been "convenient" for the Strawhats in some way. They were gladly shown the one on Zou and given information on its purpose, how to use them and the location of the two others. And though those two others were/are under heavy guard, they are also in the possession of individuals that the Strawhats were planning on confronting regardless, thus meaning that they never had to really go out of their way to acquire them.
Thus, to my mind, the last one should be the MOST "inconvenient" to retrieve, hopefully forcing Robin to do some detective work in piecing together its location and possibly even setting off a race with other factions (Blackbeard, for example) to get to it first.
Can be done in one chapter. regarding Weevil, whatever Oda has in store for him, Marco and the others will play a role in it.
If it were simply Luffy paying a visit, and maybe having some words with Marco, a couple chapters would be plenty, but the reason I mentioned Weevil is that it's entirely possible Marco CAN'T handle him. He may not be particularly smart, but Weevil's been compared to Whitebeard in his prime when it comes to raw strength and his entire M.O. has been hunting down the former Whitebeard commanders in search of recognition (and treasure). If Weevil is too much for him, then Whitebeard and Ace's graves are likely in danger. Beyond that, we don't actually know the content of Marco's message to Luffy yet.
Furthermore, if the topic of Rox and other pirates that were active 40 years ago is intended to be a big deal in the series proper, as opposed to just a hook for the next movie, a confrontation would give a chance for both Bucking and the late Whitebeard himself to have their part of that story told.
How about crashing the Reverie? How about destroying Giant Tree at Elbaf? How about killing freakin' Shanks while our heroes go to Raftel?
All interesting ideas, but we don't have any real insight into Teach's plans at the moment. Short of his active Devil Fruit hunting and a general notion that he's shooting for Pirate King like Luffy, we have very little to go on as when trying to divine Blackbeard's motives, and thus no real way to predict his actions beyond a general sense that he's probably up to something. I think a confrontation with Shanks is probably in the cards, but that's more due to past foreshadowing than anything we've seen recently. Beyond that, I don't know that we can really say anything.
There you have it. All can be displayed without any other arcs.
Since the New World, Oda generally seems to go the route of "Less arcs, but longer and with more resloving plot points". It seems to be a noticably different Modus Operandi than in Paradise (where we had 16 (!!) arcs before the time skip).
I wouldn't say that the length of the arcs post-timeskip is the notable feature, but rather how interconnected they are. Again, I don't think a couple of shorter arcs would be out of place, and trying to cram everything into the big ones may not always be viable. Sometimes the best way to give a particular plot thread extra narrative weight is to let it stand on its own.
A very interesting and welcome choice that we didn't see any Strawhats at all in this chapter. But if Raizo is in charge of freeing Luffy, I guess the others (except for Zoro) are involved in this plan.
I will point out that Chopper was actually there looking after O-tama, but you're right on this otherwise…