It does not look as though it will be a huge ask for Square Enix since they have had experience rolling out Dragon Quest titles on mobile platforms before, appearing on smartphones and tablets in the past. Dragon Quest VII would be the latest title in the series to make this particular jump.
Of course, do bear in mind that the mobile release of Dragon Quest VII will happen only in Japan at the moment, with whispers that it will be localized down the road. Nothing has been put in concrete just yet, so do take those rumors with a pinch of salt. Or you can always make an attempt to pick up Japanese, it works either way.