To sum up a few points
..Ryukku in the game for you to invade, or perhaps even Korea in an expansion. [...] But a (say) Chinese invasion a la the Mongols of CK would be unrealistic.
Yeah, I was exagerrating the invasion just to get ppls' attention. But perhaps we could have foreign representatives in your court. Depending on your character's traits. Say there's a trait: Innovative.
[...]the Dutch and Portuguese will be represented in the game, though no specifics have been given. Personally I'm not sure they should be represented with units and ships, IIRC their presence was very small and I don't think they should be a potential invasion force.
And I really hope Paradox doesn't go off-track with how advanced or powerful the foreign powers were, I'd argue that noone had the kind of force projection to justify an invasion of the Japanese islands.
I agree, the logistics of an amphibious offensive on Japan would be beyond most, if not all powers of the time.
Yeah, so I saw. But I bet this will be some sort of decision/event/modifier that helps your army rather than actual Dutch units that appear on the map. Could be completely wrong of course, but I hope not.
They will perhaps work as laws to have enacted
In the interview, Johan said that you need to have good relations with them to be able to buy muskets.
The degree of cooperation you can have with the foreigners (number of deals) depends on a combination of traits. Say you are inovative, diplomatic, unruly (I don't know much about Japan clan-Emperor dynamics, but I see it playing out a bit like CK dynasties vs Papacy. So unruly could be the equivalent of skeptic)
At its core this game, IMO, should have Japan as an essentially isolated world, but by including the Dutch and Portugese in some way it'll be acknowledged that there were some foreign influences. I don't think it should be a central part of the game but rather something that can give you the edge if handled correctly.
Perhaps the foreigners can have their own plots and schemes. Maybe it can work like the sacrifices in EU:Rome. I didn't play much, but as I understood, smaller and more concentrated religions were more likely to benefit from omens. This balancing mechanism might be served a bit by the foreigners. Colonial strategies of some nations, such as Dutch, was to prop the underdogs, so as to help them achieve a dominance, while being reliant on foreign support (in this case, arms supply)
I also think Hokkaido, Okinawa and Korea should be in as places you can sponsor raiding operations to, and that diplomatic deals with a foreign country ahould give your House a temporary boost.
We can all agree that abstract "outer world" is a great thing
Plus, gamesplay trumps history
So far, the Sengoku gameplay is promising to offer much flavor. The limited world area of the game offers the possibility for a very new (I expect this will actually feel quite different to CK because it is far from Europe, and it is just Japan) and incredibly enticing gameplay experience