For a VC to say "yes" to a company in a new market area, they have first believe that there will be a successful company in that market. The second key, that the company pitching will be that successful company only matters if the first point is made to the VC audience.
These two points are best made in this order and are better made separately. For, if you can't convince the investor that there will be a market and successful companies within it -- well then, the second point hardly matters. In my regular experience, the first point is often assumed by the presenter and all the energy goes into making the point about the company becoming the winner.
But, if the investor, doesn't believe in the market -- no amount of story telling is going to get a deal done.
The question often arises, "how do I portray a compelling opportunity in a market that doesn't exist?". The short answer is find the analogs of existing markets, make the connection as to the similiarities and use the parallels to project a reasonable future.
Making the point about the market competently will dramatically increase the chances of a successful pitch.