I think you're being a little too optimistic here. There is no shortage of web-IDE or foo-Touch on any platform. They're all poping up for all the platforms at the same time, this is not some edge Windows 8 has over other platforms. (If there is any edge at all, it's probably Visual Basic 5.0 or later)

Windows 8 will succeed not because it has a web-based toy for making toy apps, but because people still want to run Windows95 applications.