What would be in it? I have had every single handheld gaming system made except the Vita and the 3DS. And while I liked most of them just fine, it seemed that something always felt missing. Strangely enough, I think my favorite handheld was the DS XL. I don't think I care much about a handheld needing a camera, so some money could be saved there. I know I would want replaceable batteries. And for sure, the non proprietary memory cards. I would like a screen slightly larger than the XL had, and wifi is obviously a must have. And for me, no touch screen controls.
Would probably be something akin to the vita in terms of power and design but without some of the most useless features imo like the rear track pad, camera and most of its media options. If I can include touchscreen without raising production costs by much I would do it because it makes much easier to use the interface and menus and it can be well implemented in games as support to the physical controllers.
Basically the 3DS XL, but with compatibility to play Game Boy Advance games as well as all Game Boy games before that. That's it. The 3DS is my favorite console now, narrowly surpassing the Game Boy Advance.
so easy man, i will just buy any hanheld under 300 dollar and put it into a case and this is my design!