I assume that they will want to produce a demo with the least possible effort, so they will do like they did with their previous games: it's the "full" game, but you are limited to one or a few countries, and a short amount of time, from one start date. So something like France from the 1939 start date to June 1940, or Germany over the same time, or Italy from 1936-1938 or something like that. They may tweak events slightly to make them more likely to happen during the time frame (for instance, the Victoria II demo was the US to 1850, IIRC, with triggers/MTTH adjusted so the American Civil War would generally happen early enough to fall in that time frame), but otherwise the same.
That would be much simpler and take less effort than creating an entirely new scenario just for a demo, while being easier to pitch as "see the game in action".