I don't know, Ian. I think your being pretty pesimistic about the whole situation.
It's true they never had the option to "update" --- with a console that is. They have the DS, and there is the definite ability to update your firmware and/or games through the use of your own internet connection or the retial stores Download station.
The option is there, yet Nintendo and third parties have not had to patch a game or firmware. But in the other corner, the PSP is patching firmware left and right.
Now, with a console, Nintendo might have to patch some things up. My bet would be the Opera browser and maybe a couple Wiimote related patches. Everything else, except a few stragglers here and there, will not need or have patches (including third parties).
An interesting question would be, how often are games patched on the 360? That's Microsoft's console, and therefore the one with the highest risk for patched-games. If they don't patch games up much, then that might mean Nintendo and their third parties will do the same or most likely, a hell of alot lower.