Talking about potential market share is not an opinion, half of europeans not having a passport isn't either, is a fact, they can get one just to visit a theme park? Sure they can. Will they? Well, thats where opinion enters the debate, park enthusiasts already have passports, but the common citizen, judging by people I know, will just see the Eiffel tower and take a picture with Mickey.
I am not saying a park with an estimated attendance of 5 millions can't be profitable, or that it would be a shame to have it in the UK, what I think would be a shame is not having the same Universal vs Disney competition that California or Orlando have, if DLP doesn't see the park as one that can dethrone them as the most visited park in Europe, they will continue what they have done the last 2 decades and forget to about the park and any new ride that can increase their numbers, which is what I dont want, not a park in the UK