There are countless ways to extend gameplay to oinfinity:
Assassin creed Valhalla had repurposed bases ad nauseam, God of War Ragnarok has repurposed fights ad nauseam, Shadows has the same base-buster mechanic for each new area you unlock, Andromeda has male MC, female MC, love interests more than many games around here, a branching stat tree that sprung many branches and repetitive planetary missions to fill the runtime.
These are all planed out paths where MC only gets to choose when he gets on them, like park attractions in any theme park with water slides or rollecoasters: you can hop on this or that track and the game will fly your through to the end on that particular plot line.
This game could at any time tie all strains with parties, now that everyone knows everyone, MC in this or that group of girls, this or that tournament: either Chess, or debate, or cosplay, or any number of adventures once MC knows this or that girl more and can organize, using many characters in collective venues where many plot threads get tied up and make the game.
You guys might also consider that the branches discussion also includes a complete change in Genre/Medium.
Text based games without branches (not to be confused with choices in general) is the difference between a Kinetic Novel (usualy no branches, famous example Poliphonica) and a Visual Novel (branches, infamous example School Days).
I'm definitely exaggerating a bit to make my point, but no not really. The games with a lot of branching are usually short and incentivize replaying as much as possible because people want value for their buck.
The other alternative is that developers make niche projects with fewer branches that target less broad audiences. Personally I am glad some developers do one and some do the other.
Developer can even do dedicated updates with events for this or that girl: update v0.8.8 fatures the events with Gini, Amelia, Coco and Sienna. One update could finish the game on the canon route of MC hooked up with either his crush from university or with the chess player or with the gym freak - those are the major threads in the game and such groupings could work to make reasonable updates for reasonable story progression.