Larian said that there won't be any minigames. That makes it more difficult to add things like failing at lockpicking. They could add an arbitrary chance of failure, but doing that seems kinda silly.
A lot of these suggestions remind me of the Elder Scrolls systems. Don't get me wrong, I like how those systems work, but there's a pretty substantial difference in the game worlds. That difference is that the Elder Scrolls games have a very very large world with respawning enemies that scale to your level based on your level entering a zone. The base game of Original Sin has a smaller world with fixed-level enemies that do not respawn.
Mods specifically designed for renewable XP might be fine, but adding in renewable sources of XP to the base game will screw up the balance.
