So pretty much it'll last forever? Or will it eventually disapear?

How long can the ds and 3ds games hold their saves? I'm curious because all my gameboy games have stopped saving as well as some of my gameboy advance games. I love going back to see all my hard work in a game, and I don't want to lose it. Just wondering how long it'll last.

1. Brawl

2. Super Mario Galaxy

3.Zelda: TP

4:Resident evil 4

5:Trauma Centre 2