I've been to Vegas a while back, even did some skydiving there. For me it's not something to repeat, loud, hot, crowded, tons of place where you spend money without noticing it. Nothing I would consider to be repeatable. There are far more attractive cities in the US or Canada. And direct flights are not a key selling point, one stop is still ok. The key point here is to have an organizing crew large enough to handle an international crowd and experienced enough (not saying we were, but there is room for improvement).
From my own experience, estimating the number of participants is the most difficult part when setting up a bid. After the re-release of BB we didn't know how many to expect especially if we knew that we won't be able to match the Lucca price tag by far. If the WC5 is held in Europe I'm pretty confident that they match, maybe slighty exceed Dornbirn, but I doubt they will see 2000+ (prove me wrong

). Have one outside of Europe I still think 700-900 would make it to North America, maybe 400-600 to AUS/NZ. Many Europeans don't have the funds/time to save for the next 3-4 years and the distances in NA are for many Americans still an obstacle to compensate the lower European numbers. In Down Under the community is strong and stable, but they are too small overall to cover the lower EU/NA numbers.
From my own willingness, I would go whereever it will be held (even Vegas), question is: do I have enough squadmates to come along?