Seen too many good games go to shit due to heavy branching. It takes a ton of extra work slowing down the development, players and dev alike are more likely to get bored/burned out of the game and ultimately abandoned.
IMO it's way better to focus on one well fleshed out story and stay true to what made the game gather a following in the first place and that ain't solo paths. Having a romance/corruption route is already enough and I imagine adds a ton of extra work since the scenes are actually quite different. 'What if scenarios' can work, but honestly i'd rather have an update for the main plot game basically every time.
In theory there is even more work to do with just the Seduction and Corruption Route. I dont know how much BaiBai wants to work on this, but given that he clearly puts effort and thoughts into his work, it might be even more work to create scenes just with the two present routes.
Because if you want to cover all scenarios, you would need a lot of scenes when it comes to threesomes for example. Since you might not have two LIs on the same route during a threesome. E.g. if there is a threesome between MC, Stephanie and Viki, you could have both on Corruption Route, both on Seduction route or Stephanie on Corruption, but Viktoria on Seduction and vice-versa.
And this does not even include Side-LIs.
IMO going for Harem-Endings is the way to go here. And even with 4 Harem Endings which were planned for a time it should be more than enough. Solo-Endings would probably not even add replayability if done the "easy" way by having everything happening and then MC breaking up with the LIs. Because you would need to play through everything again or just make a save right before the Ending, which means you would not replay anything.
(And on a personal note I really do not like that. There was a different game here which featured different endings, but everything before the Ending was the same, even if you did the choices for the Ending during the Playthrough. So even if you wanted to end up with a specific character in the ending, you had to do all the stuff with other characters... Wasnt great for me)