A port to ARM based devices would be nice but yes, it would involve a lot of work. Only the controls and maybe graphics would have to be tuned though for it to run on windows x86 based tablets such as those laptops that can convert to tablets that HP and Dell are currently selling. You'd have to buy a high end model though as the cheaper ones are lacking in performance.
But if Larian put a touchscreen friendly control system option in there from the start then it gives people who own good enough hardware (or buy it in the future) the option of playing it in tablet mode.
Don't forget Windows 8 comes in versions that will run on ARM architecture and x86 / x64. Win 8 tablets are based on standard x86 PC architecture and some are ARM (such as used in Android devices) and they are very, very different. Windows Surface RT is for ARM devices only and won't run PC games. Windows surface pro is x86 (PC) based and uses an i5 CPU and will.