I think the core game is basically finished the polishing may take quite a while, a year or two I'd think. I like mods and tend to stick with a version for a while with mods that suit that verison. When I upgrade by several versions of course most of the mods wont work and the ones that do need updating but then again some of the mods are no longer needed as the game has improved so I usually play without mods for a while then start adding some again.
Some mods that I have used and no longer work but I think were great are
Generals bodyguard ( gives you a bodyguard of a few soldiers)
Peasant Banners ( Bannerlord needs banners among your armies )
Slow down ( allows you to actually catch things like caravans and stops you having to run all over the map I've never quite undestood how a larger army can't just send its cavalry to pin a smaller host in place to force it to battle chasing things all over the map is no fun)
More troops in hideouts ( tried different mods that did this all were great )
Some mods that seem to keep well up to date and I think are great are
Improved garrrisons ( keeps up to date and keeps adding features like patrols )
Realistic battle ( Improves armour and weapon damages to be more realistic )
The things i'd like to see added to the vanilla game apart from some version of the mods I've mentioned are
Allowing all sources of income to be viable, most people wont use all sources of possible income so dont balance it like everyone has 4 workshops 4 caravans, does some trading and loots all the time.
eg: make caravans, workshops, trading, castles and loot all provide more money, make money sinks like upgrading castles towns more expensive give me additions to throne rooms like gold statues expensive decor, tributes to gods for short lived bonuses, to let me spend that money, have really expensive upgrades for troops like really expensive armoured war horses, or faster horses, a special guard troop with minor advantages in stats but dont make me struggle financially to field a basic army of infantry archers and cavalry or garrison my fiefs.
A large defender bonus for castles ( castles should be a lot harder to take, even vastly outnumbered garrisons should be inflicting lots of casualties and taking longer to overcome, also give castles enough income to allow for a decent garrison)
Hideouts give more renown for less troops but let me have the option of taking lots more troops for less renown
Better controls in battle, let me set my troops up initially in groups 1- 10 then allow me to send each group or target each enemy group seperatley
Spawning in reinforcements is poor a better system is needed ( Possibly moveable spawn point )
Better battlefields for larger armies, Its no fun to try and fight 500 v 500 in a forest once a battle is larger than 100 v 100 more spacious battlefields should be used it might also omprove lag as the battlfield would be picked with larger armies in mind.