'Kay, I'm gonna try answer this as best as I can.
No, the Masuda Method chance is not confirmed, however I have look around the internet and I have come to the conclusion: the Masuda Method gives a 1/1300-1400 chance of the offspring being shiny.
I don't think this proximity will matter, because I can confirm it's a very broad chance of hatching an Intimidating Adamant-natured Shiny Mawile.
Getting a Pokemon with a specific nature is 1/25.
Your Mawile will either get Hyper Cutter or Intimidate, so it will be a 1/2 it will be Intimidate. (Unless the mother or non-Ditto parent has a Hidden Ability, then the offspring will have the hidden ability)
For it to be shiny, using the Masuda Method, is a 1/1300-1400.
So, multiply the denominators, and it's roughly a 1/65,000-70,000 chance of getting an Intimidating Adamant-Natured Shiny Mawile. :D
If you want the exact chance, just tell me and I'll hide it, but in the meantime, this is about the answer.
Hope I helped. :)
Source: Bulbapedia, Serebii, and mostly Google. xD