The "announcement" is here at 23:30.
It's main focus is apparently going to be about the thirty year war and and the napoleonic era. You know that time period where 99% of games won't reach because the game gets ridiculously boring once you've managed to blob up.
It's apparently going to add more depth to combat and add "customisable armies", whatever that means. There is a strangely thick line in one of the screenshots that almost makes me think of fronts like HoI, doubt we'll see that though.
From the leaked screenshots there's also going to be improvements to Africa and likely the rest of the world as well such as increased tags and provinces. However it seems like that will just make more territory for Europeans to blob into.
Ultimately I'm really disappointed. It may be a bit early to judge and things might start looking up once the dev diaries start rolling in but it just seems like it's completely the wrong expansion we need right now. The game festers while having such a major focus on conquest but so many barriers put in place to do so. Barriers would be fine if there was some other mechanic to keep the game interesting while not at war but that aspect has been completely neglected.
Perhaps an expansion based on warfare might add some things to spicen up the non-warfare aspects.
To be honest, EU4 I feel in some ways, is more friendly and inviting then EU3. But I do agree that during peace it does feel kind of... stale. All you really do is prep for the next war, but there's generally very little to do in that regard.
To compare two different, but vaguely similar, series I'd use Total War as an example. While it is doubtfully about conquest and expansion, you at least spend your downtime upgrading and researching towards better stuff. The issue I feel with EU4 is that research takes so much MP you just kinda end up doing it... eventually. And the costs of buildings means until you get fairly large - and even when you do - there isn't much reason to actually be building constantly.
It's a sharp contrast to TW where you should be pretty much building up your settlements every turn until they max out, and in later TWs, always be researching new technology. Admittedly, TW is pretty shallow for everything that isn't warfare though. I sometimes with EU would loosen up and give us more to
do rather then wait all the time. The high cost of buildings, combined with generally low income for most small nations, makes me feel like I spend 80% of my time in EU4 just with the speed maxed out, waiting for ducats to amass, so I can click a button, and spend it all in a heartbeat.