I'd imagine a massive complication to Phantasy Star Online 2 Meseta this entails a great deal of the makeup from the Japanese side of things which were exclusive to collaborations, promotional events, and events which no longer exist. The instance I can think of is that the Monster Hunter Frontier Z cooperation where I could imagine the weapons and clothing could unquestionably be provided a visual update along with everything else but that I do not exactly understand how the licensing or how the side of the cooperation works where I would wish it had been as easy as Sega going through and updating the resources but I do not understand about how much Capcom is involved in that process.

The same is applicable to collaborations like the Final Fantasy XIV collaboration with Odin (which still exists as far as I know) where I do not know how much of Square Enix is involved that for Sega to be able to update assets there. If it was purely just Phantasy Star-related items (such as character outfits, cameos from different games, or other Sega-related properties) I could envision that this likely would have been achieved, or would be done. But in the Global variant we don't have the presence of Cougar NX so I don't know if there are other complications regarding Sega's own properties that may also contribute to not upgrading everything they can within reason.

I can imagine that likely out there we'll still see someone wearing those old collaboration things even if they aren't rigged up to the same criteria as new makeup in a similar manner and that there definitely would have been outrage if it had been made unusable or obsolete. Collabs that have experienced their makeup removed nevertheless have their resources exist on the sport so those will probably still be available for jp players.

Only improvements we will likely see is the new engine improving shadows, reflections, colors, particle effects and casting them against the drapes. You may have a look how just implementing better shadows and buy meseta pso2 colors can enhance older equipment by assessing ReShade screenshots. Collabs who have had their makeup removed nevertheless have their resources exist on the game so those will probably still be available for jp players. Only improvements we'll likely see is the new engine enhancing shadows, shadows, colors, particle effects and projecting them against the drapes. You can take a look how just implementing better shadows and colours can improve older equipment by assessing ReShade screenshots.