[quote name='MattJ1991']Im thinking that they would take out the GBA slot, which would make it smaller. But then again, how would we use the Rumble Pack and other accessories .

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The Rumble Pak wasn't incorporated in that many games. You can still find it on clearance for $5 every now and then. I liked the rumble feature and am always delighted when I find a game uses it, but I don't see why Nintendo couldn't have it built in to the next handheld with an option to simply turn it off if the player doesn't prefer it.
[quote name='Cameront9']There is a "Lite" version of the Rumble pak available in Japan. NOA just hasn't brought it over here, likely because there would be no demand for it.[/quote]
I ordered the Lite Rumble Pak off eBay. A bootleg sort of version, I expect, as it was pink to match my pink DS Lite. I really like it. It's quieter than the original, not to mention it's flush in my system.
[quote name='Gothic Walrus']Taking out the GBA slot would kill Guitar Hero. Given that we've got at least one high profile, new game that's selling well and
needs the GBA slot to function at all, I don't think the GBA slot is dead yet.[/quote]
I was highly surprised by Guitar Hero using the Advance slot, as it seemed Nintendo was moving away from plug-in peripherals. Honestly, I can see GH: On Tour being the last Advance slot option. What with the highly mixed reviews, I doubt the game is doing as well as expected. While I would like to play it at some point, the $50 price tag and the fact that people are turning around and reselling it after owning it a day is deterring me.