I dont think it will increase or decrease it. A lot of blu-ray fans either like digibooks or don't. I think for those who want the digibook and don't own it already aren't going to say "well I'll just get this box set instead." I think some blu-ray fans who don't like digibooks and want a greater edition of the Wonka classic will surely get this set. But they aren't the ones setting the demand for the Wonka digibook since they arent interested in it.
I'm a digibook collector, and I own the wonka digibook, but if I didn't I wouldnt settle for the wonka box set which will more than likely replicate all the other box editions like Wizard of Oz, Sound of Music and Gone with the Wind. I can still get ahold of any of those "limited" box sets but it's hard as hell to get a Wonka digibook now.
And keep in mind, the price of the box set isn't cheaper than the digibook. Even tho its the same movie and you get more stuff in the box set, I don't think its going deter those away who want the wonka digibook from eventually getting it.