For it to work as a modern game they would have to give it so much work - like more items, things to do in dungeons, characters, story, etc... that it wouldn't even look like the first Zelda anymore.
Remaking Link to The past is actually easy - it's all there. But Zelda 1 is too ancient. Leave it as a classic. Or do a reboot, but not using the structure of the first.







