Hello,
I was thinking what could be done to make sure that the next time you decide to start a new game after completing the previous one, it will still feel fresh and would guarantee you tons of undiscovered options and missions that you could not undertake in your previous gameplay. There are some super obvious things like let's say 3 different endings to the main story and also how you decide to develop your character which will determine your playstyle, how you complete your missions etc - everyone knows about these, but what else can be done to make sure that people (like myself) who always go to every corner of the map and smash every crate they see (making their gameplay last 200+ hours lol) hoping to find 100% of the in game loot. The things I got on my list are:
1. Random loot finds and mission rewards (probably even easier to do than fixed rewards).
2. Optional missions with timer on them, that if not accepted in time may no longer be available, some of these could also lead to meeting hidden NPCs like traders or friends with benefits

etc. There could be situations where you will be given a choice to select one out of three or four available missions - you pick one, the rest is gone.
3. Your playstyle in general could unlock optional buildings for you to enter and explore (not many like these obviously but there could be a couple, each loaded with NPCs and additional quests) - not sure what would be the deciding factors for this, but this is the easiest part to come up with anyway.
4. Accepting missions from some factions that hate each other could prevent you from ever making peace with them and thus locking any potential relationships.
Obviously all of these would have be done in such a way that players would see these as choices to make that will shape the direction of their gameplay somehow, each having pros and cons. Let me know what do you think and thanks for reading!