I really hope so, a collectors edition through kickstarter or some other way would be really great!
I always wonder why this doesn't happen more. I feel like Treefrog kind of overestimated the market for the collector's/deluxe edition of Ankh Morpork (which is a shame) but, if you do a kickstarter of special versions, it's either a "no" or you have an exact number of preorders.
Anyway, I got my grubby hands on the collector's edition of Ankh Morpork (by serendipity) and would have liked to see a special version of Witches as well. The chance of that happening is slim to nil.