Since Windows 8 computers and Chromebooks will soon all have touchscreens, Chrome Web Store apps will soon be designed for touch input. A Chrome OS tablet is very likely. Google will probably make a ChromePad themselves, like the Chromebook Pixel, while allowing others to make Chrome OS tablets as well.
The main advantages of Chrome OS over Android are NaCl (x86 and ARM), more mature x86 support for the upcoming x86 tablets, and the fact that many people can use Chrome apps on OS X, Windows, and Linux.
I know Chrome OS gets ridiculed now, but with the addition of Quickoffice (which uses NaCl and will have editing support soon,) on the Chromebook Pixel and a few other apps, like a Google IDE, Chrome OS could soon be a very good OS.
Android tablets aren't selling so well now that Google wouldn't start selling Chrome OS tablets.
If Google makes a ChromePad that's as nice as the Chomebook Pixel, I would definitely consider it over an iPad.