I agree, lutes and any other instruments that may appear are probably things the player can't use, instead, you'll just see NPCs using them to play original tunes composed for the game.
even if we can't (and i have no illusions that we'll be able to) the fact that the animations are THERE means that all modders have to do is write up a script that pops up a message box and goes WHAT SONG DO YOU WANT TO PLAY and then plays the animation for the player. after that there's NPC reactions and stuff that they could work in but to actually get the player playing an instrument would be pretty trivial.
totally modding in some Russian folk tunes when they do get around to that. gonna sit by a campfire and play me some Цыганочка. i mean i could just grab my guitar and play it myself but IMMERSION.