First, I hope we have a Collection Folder or similar system so we can pull registered cosmetics (Including event and one-time rewards) out (possibly with resource or material cost) on any character. We could register any cosmetics (Outfits, CAST parts, weapon camos, etc.) and either "apply" them to our current character without needing to use inventory space for them, or simply pull out a character/account bound copy for use on the character.
Second, I hope for Beast race and perhaps some more animal-like appearance for them compared to PSU. I'm trying to keep my expectations of NGS' gameplay reasonable and not get overly hyped because it's going to be a while until we get to play it, so I wouldn't dream of Beast being added unless they were justifiably different from Human/Newman/Deuman/CAST so I'll probably not see this happen.
Third, I hope even though NGS takes place 1000 years after PSO2, I hope we see some returning characters or at least the ones that can't live for 1000 years be memorialized or referenced in NGS' ARKS structure and Oracle Fleet. It'd be awesome to see the non-CASTs that can't live for a thousand years get memorials in the Shopping Plaza or similarly appropriate place, and even better if we can see Regius, Maria, and Zig still kicking around after all this time (And Saga to boot, no pun intended).
One of my biggest peeves with PSO2 right now is event-exclusive or one-time reward cosmetics like the Hero weapon camo we might all get if the twitter gets enough retweets is that I have 5 characters I'll wanna run Hero on and only one of those cosmetics...
I'd also love an ability in the UI to set up an auto-sell or auto-dismantle for specified item types, rarities, etc.
Overall, I'm hyped for NGS and hoping my CAST triplets and Human and Deuman will fit in well.