I'd definitly buy it; hell I have been wishing someone would make OOT2D then port it to the DS or something just to have the game with me to take to work.
For those who want a new Zelda game, it's called Phantom of the Hourglass. Most ports are send to a 3rd party company and would not take away from development time from the main team, so porting would make little difference.
How to you port stuff to ds?
In terms of the real OOT? Nintendo would give a company all of it's source code and resources(graphics what not) to another company and they would take the essence of the code and re-write it around the DS hardware.
In similar terms of OOT2D; it would be taking the code(much harder to do if it's in GM) and writing it through homebrew software so that it can work on the DS's hardware, as well as converting all the sprite and maps so they fit default resolutions etc...
Nintendo DS uses a mixture of ASM/C/C++ to run... not sure of the N64, though I'd want to say ASM/C/C++ as well.