Ugh, I would hate for any company to start selling patches, mostly because I think patches are bullsh*t to begin with. More importantly, the first company to do this is going to open the floodgates and I don't like the implications of such. Patching already encourages lazy programming. "Oh, release the game with glitches anyway, we'll fix it later." I remember when developers absolutely could NOT "fix it later" and had to make their games correctly the first time. Once we start paying for patches, we basically surrender ourselves to buying broken games for $50-$60 then another $5-$10 because the developers didn't do their jobs right to begin with. And who's to say 3rd parties won't start doing that on purpose? That's not even additional content by DLC. Instead of getting content that's one, probably on the disc and requires only an unlock code and two, should have been included in the retail release in the first place, we could potentially end up paying extra for lines of code that amends and overrides the original shoddily written code and nothing else. Shenanigans. We're already living in a world where Nintendo is attempting to sell a $300 handheld, probably coming close to doubling the cost of parts and manufacturing.
In Super Mario 64 DS's case, ignoring whether patching DS games is even possible, Nintendo could sell this as DLC (something I'm also not a terribly big fan of but that's a different topic). At the same time, Nintendo would essentially be saying "exchange your so-so controls for sweet, sweet analog control... the way it was ALWAYS meant to be played."