If Elbaf is story like Skypea, where the SH go to a place "outside" of the world and without a lot of companions and side characters would be what i want mostly from OP. Since PH theres soo much people around the SH that we cant ver focus on them.
If BM is defeated the SH probably will get to Elbaft already being seeing as good guys by the Giants, there probably will be a small conflict with Loki, and them the meeting with Shanks(hope for a Davy Back) and the last Road Poneglyph and them finally Laftel.
Dont think there's a need for a Loadstar arc, the SH already know about the Poneglyphs. Only if Loadstar is the place from where u sail to Laftel, but that didnt seems the case with the Roger Pirates. If Nami need to develop more her navigator skill, will be making the map to Laftel and getting there, there's nothing bigger a navigator could achive than that. And of course remaking the GL without the log pose to go to Marijoa for the Final War will also be big.