I really don't see the Windows RT based tablets doing much in the future for Microsoft. Once consumers realise they're simply running gimped versions of Windows 8 (and with a lot less apps then Android/iOS) they'll just go for a proper Windows 8 tablet/laptop device, an iPad or a cheaper Android tablet.
I do see businesses buying into the concept (of full x86 Windows 8 tablet/laptops), especially for business users that do a lot of travelling and need an easy to use but capable portable device. The problem for Windows 8 though is that the touch interface and the traditional interface are kept fairly separate. For instance, why doesn't the browser retain the session when you switch between interfaces?
Anyway, I don't see Microsoft making any major inroads in the current tablet market, Apple and Google seem to have tied it up between them. However, the current tablet market isn't really catering to business users and I think this is where Microsoft will make significant gains. It's an untapped market segment.