Features that I’m describing here could be entirely optional to the player, if they decide to spend time utilizing these gameplay mechanics it could potentially benefit them greatly, but if they decide to never interact with them it would not negatively effect their progress or speed of it.
IRL there are a lot of interesting mechanics involved with trading shares of publicly traded companies on the open market.
Hostile takeovers, buybacks, market crashes/bubbles, penalties and fees, dividends, penny stocks, blue chips, day traders, long term investors, different types of accounts and their beneficiaries (your character dies eventually but you could pass on the empire you created to a family member that the player then “starts over” with with their new inheritance) Inheritance could be a smooth way to transition the player from the end game of story mode into a “second playthrough” as a family member of the original character, but this time in sandbox with all the extra goodies.
If I’m done with a business I currently own I could sell the majority share of the company to potential buyers on the open market or maybe even private buyers, assuming the player has the prerequisites to do so, this could transfer ownership to the AI (or maybe even other online players that are bidding!) and make the hassle of transferring items/resources from old business ventures you currently have no interest in pursing into the new venture(s).
A lot of these mechanics could potentially pair well with online multiplayer which is on the roadmap as a potential feature in the future. Possibilities are quite endless and could add a significant amount of replayability to the end game.
Apologies if any of this has been suggested already.