The four richest regions in Spain are Madrid, The Balearics, Cataluña and the Basque Country – in that order if I am not mistaken.
All the communications work on a hub and spoke system, meaning that everything is focused on Madrid. It is the capital of the country so the greater movement of passengers (plane, train and bus) is to/from Madrid.
The airline hub, without doubt, is Madrid with all long haul Iberia and Air Europa (Skyteam) flights leaving from Barajas. Barcelona is secondary. Vueling is promoting Barcelona as a hub but at the moment it is limited to European flights. If it were a successful hub for long haul I do not doubt that(since Vueling is in IAG) Iberia would provide the long haul flights.
I see no change in the short-term. France is irrelevant except for the passengers from the French Basque country who wish to fly to Madrid or Barcelona from Fuenterrabia/Hondarrabia(San Sebastian´s airport) which literally straddles the frontier.
Independence is, at the moment, just political hot air. It is not on the cards at all for several years. If, down the line, independence were granted to Cataluña then Barcelona would have greater protagonism as a hub. But as a long haul base it would up against Barajas and Lisbon making the struggle an uphill one.