Now that even cheap laptops are coming with touchscreens I was wondering if Canonical plans to include its new touch version of Unity GUI on regular Ubuntu for use in laptops and desktops.
Unity already supports touchscreens. See, for example, this article. Unity was made from the very beginning to work the same way on different kinds of devices with different kinds of input hardware--that's why it's called "Unity".
So it's unclear exactly what it would mean for the "touch version" of Unity to be ported for desktop use. Not much information is available about Ubuntu for Phones yet, and it's not available for use or testing, so it would hard to answer highly specific questions.
Right now, we don't know what changes, if any, will be made to the phone version of Unity but not to mainline Unity. For all we know, they might end up having the same source code (perhaps with some differences in configuration or build options). From the official information about how Ubuntu for Phones works, the interface is shown to be operated in the same way.
On the other hand, perhaps there will be extensive changes. After all, Unity is a Nux plugin for Compiz, which may not be available on phones (or may work differently) even by the time Ubuntu for Phones ships.