Not another crew, we already have decades of SH, Oda would do something very similair to that, better try to see something new instead of the same soup.
And I would like to see something more mature in themes (but that will never happen).
So something I could enjoy... Mihawk's rise from nothing to WSS, it would be something like One punch man after Shanks loses his arm.
Akainu, his rise, and how he developed his concept of justice (can see his grudges for pirates are caused by some heavy loss).
Moria's story (even if I hope for a good ending).
Anyway the possibilities are endless with all the interesting side characters that exist in OP (litterally several hundreds), but most likely if this ever happen (and in any case it will be a lot of years from now) it will probably be the son of Luffy, Shank's or something on these lines and it will be another OP story (see Boruto and the likes).