The 650d most likely won't have a huge iq improvement, it's about features (video af, touchscreen). In any case, if you wait for it you there won't be much summer left to use it... concerning your speedlite you should check if it has the ettl, or you won't have much fun with it either on the newer digital bodies.
Not interested in a touchscreen or higher MP count so much., but the video AF addition would be a big plus, and all auto focus points for stills being more like the 60D would be nice. BTW, my Speedlite is a 420EX, which is supposed to be compatible with most features.
And if you're so set on iq, either Nikon or Canon are a wash, because it much more depends on a good lens. Personally, I got the 60d over the d7000 with the better specs because I just like the usability of the Canon better and it runs a hacked firmware (magic lantern) which adds so much more over out of the box Nikon.
That's the tough decision. Because of it's better ergonomics in my hand (more dedicated buttons, familiar menu) I feel like the Canon is more fun to use, and so what if the Nikon has marginally (?) better IQ, but I don't really
want to buy both, shoot a bunch of photos and return the one I don't like as many people do (Costco has both models and that great return policy). I did read about ML and forgot what "features" it adds, but sounds like a nice bonus.