I see no reason why Skyward Sword will be the last Zelda game, or even why it SHOULD be the last game. Nintendo still make a lot of money of of the series, so they would not want to end it now. And frankly, fans wouldn't want it to end yet either. Nintendo is still producing fabulous games that we love (and will buy).
As for the remakes, they are just trying to make more money off of fans. As opposed to some, I have no problem with this. Ocarina of Time is a great game, and if Nintendo wants more money from it, so what? Now I get a chance to play one of my favorite games on the go without having to always be at home to play it, and some new fans that haven't experienced the game yet will get a chance to when it releases.
Take Final Fantasy for example. Their games have so much hype, and some of them don't please fans at all, but they keep making new games. Why? because it makes money. The same thing will be true for Zelda, except I hope it never goes downhill.