Well I think part of it will be how difficult it is to port the game and the initial features to Ren'py in the first place. This does have the advantage that the original BB is IMO nearly complete with what honestly would have been about 3-4 updates of realistic material left in the first place. How well you want to do it is the other question, and I mentioned some of the issues design wise that also likely contributed to the Eric cuts more than just a marked distaste in a portion of the fanbase for NTR. Now routes or changes have to be designed with the ability for them to merge in seamlessly with a later route. During the design process this could be difficult especially if the end game scenarios aren't done, but DS also made things much more difficult than they needed to be.
One example is the Lisa/Olivia route. That route simply ended because it was difficult to merge into the sex-ed route and vice versa according to DS. I found that a bit odd as all of the NON Sex ed scenes (original Sex ed, not the abomination that wasthe Ann sex ed route) could easily take place after they were unlocked with the Olivia route, just with slightly different dialog. Or coming from the other angle, instead of a completely different and boring new olivia story on the girlfriend route with Lisa you could have started bringing in the scenes with Olivia and Alex, and just ignored the part with Lisa and Alex, not a lot to be lost there.
The funny thing is because of the layout of the game, the proposed Eric additions are probably going to be the easiest things to add. Alice doesn't need to change her story at ll if Eric fucked her before Max. The only one that would have to change would be Lisa, her sex ed with Eric could run concurrent with an Olvia storyline, and Eric's sex ed could replace the MC's attempts on the girlfriend route. The hooks are there for Max to peep on the lessons, and the only reason DS didn't do it was to avoid another uprising. Whoever pops her cherry, well with a couple of dialog changes, are all that would be required. You could still reuse all of the Lisa/Max images later, maybe with 1-2 different ones, and just change the dialog. Hell if you wanted to go real lazy just add one or two lines that she pretends she is a virgin, when she isn't.
What all of this does take is planning, and that is something I think it was clear was more than a bit lacking in the original BB release. THe problems in that game were manifold, and I'm sure my rants in the original BB thread are still there, and worthwhile. The key is not making every route completely different, but figuring out how assets can be reused between them. A peace with Eric route would be mainly differences in Dialog for Max, but maybe he can get some on his own, or maybe have 1-2 sharing scenes.
What I think is harder to fix is some of the bad design decisions that happened as the game got more linear. Alice's sudden rise to dom status from sub came out of nowhere. The Ann sex ed quest had great renders but was nothing more than ANOTHER attempt to delay vag with Lisa. Olivia 2.0 was hot garbage and so on.
I do agree with you on how difficult it is to choose how to do updates on an open-world game. Polls are generally flawed because it keeps the focus on very spefiic characters, and fans of that character tend to be more likely to become patrons then, while fans of the ignored characters tend to fall off. This makes each subsequent poll skew in favor of whoever won the last poll. Look at MILFY for an example of that.