I'll be astonished if Disney base the ship out of Southampton; you just couldn't offer decent 10 and 11-night cruises as it takes a full 3 days just to get into the Med (via the dreaded Bay!), and that's not practical unless you have 2 weeks or longer (or if you make it a one-way cruise; i.e. So'ton-Marseille and vice versa). Disney really want their guests to be able to take advantage of the ship from first minute to last, and that usually means round-trip cruises from somewhere warm and hospitable to start with.