Seeing two things tablets have over laptops 1) much better battery life 2) more portable
with the advent of affordable bluetooth keyboards, there isn't much left to differentiate a tablet from a laptop. even Microsoft Windows is following suit, having their full version Windows 8 on their tablet lines, making even PC apps/games an eventual possibility on their tablet lines.
An iPod touch can do far more than a Zune. it can do wifi, apps, games, pretty much all the iPhone does, except phone calls (and that is also debatable given apps such as Pinger and Google Voice having iOS ports) as for the Shuffle, it is only $49 compared to the Zune's $399, and last, the Zune is still a Microsoft product, one could say they're even tighter locked down than Apple products. Apple just washed them away, as did Android
you can buy an MP3 player for less than $19 today. the only benefit of buying just an MP3 player (with no other functionality) from MS or Apple is to show off a label, nothing more.
"If you treat your system like a kiln, don't be surprised when a brick comes out the other side."