I have a trip booked to Niseko again this year (March) but next year would love to try somehwere else. The hubby and I are into the snowboarding but equally into the food and relax aspects. Your business idea sounds like it would appeal to the time-poor set, if you could offer the full package - ie arrange airport transfers, accomodation, show the best places on the mountain and some technique improvements. We are expats living close to Japan (on a formerly Japanese island) and did consider branching away from Niseko this year but decided in the end due to our lack of language skills and tight schedule that we'd stick with the known area.
By the way, do you have any good contacts or recommendations for some instructor/guides in Niseko? We're considering taking a private guide for some good off-piste without ending up having to walk out of gullies etc.