Despite still not liking the modern UI myself (to the extent I hardly ever use it, thanks MS for adding the option to return straight to the desktop when no apps are open), I must say that I moved to Windows 8.1 a month ago on my home all-purpose PC and I never looked back since.
UI-wise the desktop theme looks neater, performance-wise it feels quicker and more responsive than Windows 7.
Still I would have liked the chance to customize a little more the start screen (I'd love to have native wide tiles also for desktop apps for example and the chance to manually select the background color), but that's a marginal issue.
As for WP going away... No way. For what I've seen from my mates' Nokia phones (on my phone there's currently Android) WP8 is a very good mobile OS so I don't see why they should be dropping it.
The same goes for Windows RT as far as I'm concerned. If you need a lightweight laptop to carry wherever you go and just need Office/internet and social networks/mail/news and forecasts and maybe some little game to help you wast the time in which you're not working, RT is a more than viable option.
It also spares you from forking out for an Office license, and this is not a small deal.
My 2 cents anyway.