Dream Lad
Banned
The reason why a girl won't get the Brock treatment and last a long time is because the female companions are the most marketable characters each saga after Ash, and they want a new one to represent each gen of the games. The female companion is always a major driving force of each saga, and given how popular the designs are leading to tons of fanart, character interactions, etc, it makes sense to have a new one.
Why can't they stick Serena (or any girl) in the Galar female character outfits?
It seems like their comment was taken out of context then since it sounds more like they meant that the kiss was just a way to give Serena's fans hope that she and Satoshi would reunite someday, which might still happen, but that doesn't necessarily make them an endgame couple.
Well if the implication is that they'll be the eventual endgame couple when the show (or at least Ash's journey) is over, it would be very odd if there's just a scene of an older Ash and older Serena together without any explanation. You would think they would bring her back quite a number of times in subsequent seasons if that's supposed to be the ultimate result.