I have been waiting for this Dev Diary, and I can say I am cautiously opptimistic based on this thread. What I have found most disappointing about the nature of the game is that after the first 200 years, every nation I have run played the same. Same settings, same ability to defeat everyone that opposes me, and worst, all the events, rulers, even units were the "same". If I was playing Castile, became Spain, and conquered all of Iberia, then I had the EXACT same experience as Aragon, becoming Spain, and conquering all of Iberia from that point on. The rulers would generate the same, the generals would generate the same, the events I get would be the same. Same, Same, Same.
These new events sound like they may provide for a longer lasting impact from earlier event choices. Thus, if Aragon chooses "veto", even if I become Spain, I still have that effect. Castile might not be able to shift to those settings in time to have that event, and thus, Castile Spain would play differently then Aragon Spain.
I hope this will include things like the Religious wars of France, and Civil War in England, things that if the existance of the right prereqs exist, and those prereqs are commonly found in those nations for which the historical nature of the event models, then I can expect that France will be more likely to have religious wars if it has multiple religions, or England will involve itself in a civil war if the hundred years war is lost and civil strife insues.
Incidentally, this is one of the big things I think is missing from the current set up. Same nation Succession wars. Basicly, two factions in a nation face off for control of the country. It would require a special form war, just like the Succession war does, where in you would be able to forceannex the entire other faction without bad boy. The idea of it being a large rebel uprising just wouldn't quite capture the feel of a Civil War like the War of the Roses.
Personally, I'd like to see more of the "historical" events intended to be added, so I have a better feel for what my gaming experience would be like, if that is possible.