2. How quickly will the budget airlines set up touch-and-go routes to other countries? If you're flying from Paris to Marseilles, make a minimal stop in Barcelona or Turin.
I just checked a couple travel sites. Full TGV fare is around €100 and Ouigo (very fast cattlecars) is as low as €20 for a 3.5 hour train trip from Paris to Marseilles. Some budget airline was €81 for a 1.5 hour flight tomorrow. I didn’t check longer notice flights.