I don't have anything against the ideas being posted here, but I think that those alone wouldn't solve the "end game" issue.
They need to fix the campaign AI first and foremost... none of it makes sense in the way they choose their targets, or that they choose targets in the first place when they are HEAVILY outnumbered instead of focusing to defend whatever they have left that I am conquering one target at a time before going back and retake whatever castle they have managed to get which was left there with a 20 men garrison.
That should go along with a change in the absurd number of lords/ladies that keep taking to the field as you capture them, making it an endless grind to finally halt them from acting like a respawning locust swarm that will keep making tiny armies of peasants just to tick you off. At one point I had 80+ prisoners from a single kingdom, and yet they would somehow keep making peasant armies out of nowhere.
In my current game as I started to steamroll, all factions ended up declaring war on me and no longer declaring war on each other. "Wow the first thing that makes sense that I've seen the AI doing so far!".
Which would have been fine if it wasn't for the fact that the AI stupidity as per above AND the AI stupidity when it comes to kingdom decisions (insisting we sign for peace against a faction I've got 80+ prisoners while they have 0 and haven't made any gains in territory, only losses) which makes it an unnecessary and unfun grind. For as many thousands of influence I may have gathered at some point, they often make you waste 1200 influence for each stupid proposal you have to say "no" to, until when you can no longer cause you are out of influence.
Instead of aiming to artificially make the game last longer with their "snowball control" AI of "let's act against our own interest for the sake of the game lasting longer" (like when at the beginning they propose to declare random wars just because, forcing you to stop wars that were going well elsewhere), they should focus on making the AI try to fight and act smarter without the insane priority they have at the minute towards "kamikazing" to get your least defended castle on the other side of the map while you wipe them off the map.
Once that's sorted, the game could definitely use more content to make it more interesting. But first and foremost it would be good to see it actually fixed. Let's not even get to the main quest which I tried for the first time since EA, thinking that by 1.2 official release it would be working with no bugs. By the time I assembled the banner, I was already the kind of a pre existing faction since our king had died in battle. Turns out I couldn't offer the banner anymore and thus the quest failed, unless presumably I decided to give up on being king (and why would I?).