The hard part isn't the hardware, the hard parts are the software and the politics.

I'm pretty sure that I've used every single feature of the TI-83+ software during my 9+ years of education (grades 7-12 and undergraduate). If your new software is missing just 1 feature that the original software has, it won't fly with educators.

Also, even if it's a massively successful kickstarter, TI can still spend more on lobbying to protect its monopoly ;)

That being said, please try it! I'd love to see an open source alternative!