Although a high proportion of those living in Yorkshire may be using airports outside the region, Finningley will not address this because the services which are going to operate out of there are pretty much the same type, to the same destinations, as already exist from Leeds and E Midlands.
These two airports have a fair (not large) choice of low cost and IT destinations, a handful of European business routes, and no long haul schedules. And that's exactly what Finningley, long runway or not, is going to provide as well.
Press speculation that it could attract the likes of Emirates, American, Lufthansa or even BA, is just uninformed column filling.