I sort of think of the DS/DS Lite as the "next-gen" Game Boy anyway.
Although I will be sad when they stop publishing new GBA games. I play a lot of GBA on my PSP thanks to Exophase and the amazing gpSP. It still appears for now at least there are a few GBA games still trickling out each month.
I had just about all the Game Boy systems over the years. All except the Micro because I'd like to keep my eyesight.
The Game Boy will always live on and be preserved in my PSP thanks to the great emulators.