All that is required is for the Spanish end of the high-speed train line to be put into place. The exact journey duration has not yet been unveiled, but with existing trains from Paris to Perpignan, the French part of the route, taking under five hours, it would seem that the 1,000km journey from Paris to Barcelona should take around six. That's city center to city center, with no need for extended check-in times or getting to out-of-town transport hubs, and no hand baggage restrictions or surly customs guards.
Spain has the most high-speed train services in Europe. The AVE, as it is called, for many years only ran from Madrid to Seville, but has since expanded to Madrid to Barcelona, Madrid to Malaga and a few minor routes around the country.
Read more about the AVE Train in Spain