I think this is going to be a big undertaking. As much as I'd like for all the features of specific packs to roll into base game (like Seasons and Pets), those have always been expansion packs so I doubt they'll undo everything they've done in previous versions of the game for the Sims 5/Project Rene. The Base Game has always been a teaser; small changes to graphics or the UI, maybe different look for the Sims overall, but it isn't going to come fully loaded. As a player, it's up to us to choose what DLC we want to purchase and how we want to express our creativity in the Sims.
However, I'd like some base game features that they ended up patching into the Sims 4 to be a part of the base game in the Sims 5/Project Rene. I'd like the infants and toddler life stages, basic body hair, pronoun and romantic attraction (similar to the Sims 2 where they can like certain physical characteristics or job types), likes/dislikes (just based on color, music, food, and maybe skills), a calendar system to see birthdays, work days, holidays, and schedule events, bunk beds, a couple after school activities for teens and children, being able to lay in bed to read or watch TV, scooting across a double bed, random calls on the cell phone, etc.
I agree with the option to toggle features on/off should be a given for every new feature in the game as they don't always make sense for every save. I like that werewolves can be regulated to the world that came with the pack so I don't see werewolf sims in every town. They should also allow a toggle for fears/wants/whims, weather, celebrities, etc (if those are a part of Project Rene in base game or from DLC).
Of course, base game features should be considered and sometimes updated with each additional DLC; so far example, likes and dislikes could be updated to include weather preferences when Seasons is added to Project Rene or after school activities can add one more variety if there's a generations or school expansion pack. I want Project Rene to have more cross-pack compatibility and features to continue to grow as the game grows. Concepts/features shouldn't be a one and done, especially when certain theme continue to build across DLC. They really dropped the ball for TS4 HSY EP because it didn't work smoothly along with Parenthood; the discipline system should have had some overlap like grounding teens for missing school or dropping out but it didn't.
