This is a heck of a start-up operation. Substantial sums of money would have to change hands before this project could become a reality. Given that it's unlikely that this virtual airline would have assets to secure adequate finance, the individuals involved must have deep pockets or supportive private backers.
I've read a few posts pointing out that Swiss have demonstrated there is a demand for what PowdAir are planning. There is one difference. To Swiss it will just be a route - not for one moment will the flights to Sion be 'make or break' for them.
One last thought. What exactly does an airline, that seems to only exist for the benefit of those partaking in winter sports, do when then snow on the piste melts away?