The focus of this theory is the colorspread of the chapter 941. To my knowledge the topic has still not been discussed, but I could be mistaken (didn't have much time to look around..).
I think that there are substantial hints concerning future developments. Let's look at the colorspread
As you can see there are several destinations pointed by the sign, and some characters are clearly pointing in a way or another to the direction they want or maybe will follow.
First of all, the road they are walking on starts from "Home" (the direction of the reader) and leads to two mysterious places: "Arcadia" and "Hell". As you can see the arrows on the road point towards these two places, so it is clear that while "Home" represent the past, "Arcadia" lays in the future. This Arcadia could be the next (or a future) destination of at least some of the SHs, and may turn out to be a hellish place, even though the name Arcadia usually means utopia.
Let's now see what other hints we have:
-Luffy: wants to go to the end of the sea, which may be the same direction the road is leading them since his thumb is also pointing towards the back;
-Chopper: wants to go to the cottoncandy kingdom (see his shirt), which is actually a direction in the sign! Maybe this could correspond to a real "sweets themed" place in the OP-verse like Tottoland or the Sorbet Kingdom..
-Sanji and Nami look like they will follow the road as well: Nami is looking for somebody to carry her in that direction (she wants to go to the spa) and Sanji will either follow her or the reader, therefore proceeding along the way.
-Now to the real point: Robin!!! She is holding the "Good Place" sign, and we can see that the "Good Place" direction is the same of "Home", which we can associate with the past.
Maybe this is related to the history of the dark century which Robin wants to investigate, a sort of golden age in the past (a good place?), maybe before some accident happened. But this is not the end of it: a sort of graffiti crosses out the "Good Place" direction and even warns not to follow that direction!!
Will Robin be in danger if she pursue her historical interests?? It really sounds like a bad omen, and could be related to a possible kidnapping of Robin, which is something that many believe likely to happen by the hands of BlackBeard.
Moreover Luffy's and Brook's arms are reaching to her, as if to grasp her!!!
Note also that Robin is the only Straw Hat with her luggage ready, which may indicate to a forthcoming departure from the crew!
Interestingly, the pink sticker is from Dress Rosa. I cannot figure out the others but you can see that there is a sticker that partially covers the one from Dress Rosa! The light-blue one, figuring a greek temple-like column (which recalls the archeology theme) with something like "GR?N" written on it. This also could be a foreshadowing of her future travels and perils!
(though it could simply from Green bit..)
-Note also the shirt Franky is wearing: "(Ne)ver Walk Back Way". This seems to stress even further the warning of the graffiti!!
Other than this Brook seem like he will follow panties: whose though? Maybe Robin's, since his hand reaches towards her.. but who knows;
For obvious reasons Zoro does not have a direction lol.. (directions are not his forte);
Also Usopp appears not to give any info, except being interested in the road itself, which may eventually mean that he will follow the road.. But of course this could be reading too much into it.
The two directions of "Arcadia" and "Good Place" are in some sense dual:
- the first is the only one advertised while the second the only one with a warning!
-one points to the future, the other to the past.
-both the names of the destinations indicate a peaceful place but in both cases this seems to be contradicted by the "Hell" sign and by the graffiti warning.
Speculating one could even think that they point in some sense the same place: maybe at the end of the story some ancient order could be restored in the world (which I think is the content of some speculations but I'm not sure). Funny enough, geographically this would make sense cause the Earth is round so two opposite direction will eventually lead to the same place.. alright alright..
Before concluding: I left out the "Somewhere" and "Beach" directions, which I don't think could have a particular meaning. But who knows..
Now the conclusion:
I think the colorspread gives very strong hint to Robin's future kidnappig or trouble related to her being an archeologist, and foreshadows one of the future destinations of the SHs.
So thanks for reading and let me know what do you think!