How would the Unity path Canonical is going through regarding desktop environment affect the other flavours of Ubuntu? I mean official or almost Kubuntu, Xubuntu, and perhaps others not officially supported variations will follow a different path...
Most likely it will not affect them at all. Kubuntu and Xubuntu are community efforts; there is very little direct contribution from Canonical to these projects. For instance, I believe that there is only one developer paid by Canonical working on Kubuntu. Xubuntu doesn't have any. Canonical's main contribution to these projects is infrastructure.
Each of these projects has been driven by the strong communities which have grown around them. The fact that Canonical has decided to push Unity will not change that. In fact, if any thing, I wouldn't be surprised if the community ends up creating a new "buntu." I imagine that there will be people interested in working on a stock GNOME derivative. Gubuntu perhaps?