Basically don't update for now if you use ironhax, as 10.4 now requires you to install a games update before letting you play the game, meaning it will not let you into the 1.0/1.1 version of ironfall. I don't yet know the status of menuhax and browserhax, but based on the amount of things that were changed they might be gone as well.
Also has anyone tested if Nintendo patched the kernel exploits that were in 10.3?
I also hope Nintendo realizes how much this affects even those who don't know about homebrew. Seriously, if the update thing applies to all games, you could have your 3ds detect an update while you are home, but you don't realize it and when you are away from home and want to play your game, you're SOL because nintendo won't let you play the game you legally own due to it not being updated. I sincerely hope they made it only for ironfall, because if this affects other games that's just stupid.