It would be nice to see some of these have a return to the series. I mean, Gleeok was in Phantom Hourglass, but with the 3D Zelda games, you have your perspective different than just an overhead look at it, the bosses would be more animated and made larger in scale to Link. If Nintendo were to make a return of these, I would at least hope they put up a decent challenge to the player.
The only thing about the bosses from the NES games, is that there isn't really too much of strategy behind beating most of them. Some of them is just luck of randomly stabbing with the sword and placing a few bombs. Why I am saying this, is that the item obtained in some dungeons were not used in the boss fight at all. No one is going to attempt to fight a 3-headed Gleeok with the Magical Key.
If Nintendo reconfigured the entire boss battle into something epic that required a special technique like the newer games' bosses, then these would certainly make going through a dungeon to work up the the boss well worth it. The classic bosses have some really great designs, so I think it is a great idea. I'm really looking for the return of some of the bosses from A Link to the Past as well, such as Trynexx.