Ive thought about this a fair amount, as trade in the open world would be rather boring what with just waiting to arrive at your destination. I think if you look to the actual age of sail for inspiration you can find some great opportunities for game design that features a well modeled economy that serves a combat driven game. For instance, you can have more 'fixed' demand trade routes, like sugar, slaves etc (though that would be a controversial addition). that pirates, privateers and frigate captains alike will be able to take advantage of, High profit = High risk. Then you have lower demand goods that will fluctuate based on regional needs, grain, military supplies etc. If you have a vaguely simulated war between European powers this would work nicely. The fixed routes would encourage group play, the lower demand lower player numbers. I can already see this could be open to exploitation, if say a lower demand route is profitable enough for a large group to run in relative safety. Essentially what i am getting at OP, is that what your describing should happen naturally on the open world based upon smart and nuanced economic modelling that feels authentic to the period. There are so many opportunities in this period for accessible game mechanics that immerse you in the game without feeling artificial, forced or heavy handed. While a dedicated scenario encounters mode is a good thing, it should be an organic thing in the open world. Yes scenarios are easy to develop, systems are harder, but they also improve longevity. Ill leave you with this, Your a Spanish trader heading back to Spain, your at war with England. There has been a large battle near Havana so you decide to stop near there to resupply the port with military supplies and soldiers. The Royal Navy players know this as well and so are dispatching lots of frigates to the area. On route you encounter Three of them! luckily three Spanish frigates from Havana have been shadowing them as well, and upon seeing you they move to engage the English frigates. If they delay them long enough, you can get the supplies to Havana for a huge sum, if you don't Havana will likely fall. If the open world encourages scenarios like that to play out, this game will have a player base for along time.