Will mission trees be removed from future versions of the EU series? I think there was a comment from the development team that they regret adding it to EU4.
I really hope they do not remove mission trees altogether. I like that different tags play differently, that there is different content for the tags and that the game nudges them into a historical/historically plausible direction.
What I would like to see is mission trees with alternative and often mutually exclusive branches, i.e. basically a mission system that is more like the national focus system of Hoi4. Right now, there is one set of missions for each tag and the game incentivizes you to complete all of them. Which basically means that the missions encourage exactly one style of playing a country. This means:
1. Low replayability. Once you have completed all missions for a tag, the mission system doesn't give you any incentive to play that tag again.
2. Less strategic decision-making. Since you can always complete all missions for a tag, you are not really forced to pick between different options. There is only a decision of
when to complete a certain mission or a certain branch of missions, not of if you want to be able to do one thing or another. You can always be, for example, both a colonial Portugal and a Portugal that conquers all of Iberia.
3. Less player agency. The mission system encourages one specific way of playing a country rather than letting you pick what kind of playthrough you want while still interacting with missions.
A system that would let you pick different "paths" and where there are real decisions and real opportunity costs and real decisions would be a lot more interesting.
This is done better not only in HoI4, but also to a certain extent in Rome's mission system where there are (sometimes) missions that are mutually exclusive.