I'll elaborate on this.
When you boot a DS game, the ARM7 processor boots first. All current DS games have an ARM7 executable. Removing the ARM7 will render all DS games unable to boot.
When one screen is 3D and one screen is 2D, the ARM7 is powering the 2D screen. When both screens are 3D (several games do this; there is a framerate cost associated), the ARM7 is not powering any active screen. Removing the ARM7 will render all DS games with a 2d screen (80%+ of the library) unable to display.
When you touch the touch screen, the ARM7 handles your input. Only the ARM7 can do this in the current architecture. Without the ARM7, no past DS game can access the touch screen, and if future games used the ARM9 given a new hardware architecture, no past DSs could access the touch screen using the ARM9.
Any time your DS uses local ad-hoc Wifi or Nintendo WFC, the ARM7 is driving this connection. Without the ARM7, download play, wireless games, and WFC all cease to work.
The ARM7 also constitutes just under one third of the DSs general processing power. Removing it will not only break existing games, it will kneecap the DS on a go-forward basis. I guess the bright side would be instead of being video-constrained in terms of gameplay opportunities, it'd be processor constrained. Yippie!
I hope people continue to reply to the thread suggesting that the ARM7 will be removed.