The basegame is Warband++. It's not wildly different from Warband and follows the same template. Exactly what you want out of a sequel. If they had turned Bannerlord into an MMORPG or did what EA did to the Command and Conquer series, we'd be all up in arms.
But the true power of Bannerlord is in its modding tools and mod system. Being able to run multiple mods concurrently in a Skyrim style fashion instead of being locked to 1 module at a time means there's as much potential to grow as Skyrim did. Countless new quests lines, items, enhancements, etc.