So you're saying there wouldn't be tourists in Miami? Are you familiar with Miami as a tourist destination currently?
That's not what I'm saying, and I've repeated this point ad nauseam. Tourists who are going to take time off work, pay air/gas fare, look for hotels, etc. for a theme park trip are going to go to Orlando, plain and simple. The tourists that are in Miami aren't there for theme parks (obviously). And there's no reason to think that all of a sudden, tourists are going to either
a) pass up a vacation to Orlando to go to a theme park in Miami instead of Disney or Universal
b) add on a trip to Miami from Orlando just to go to more theme parks
If we were talking about some type of theme park with proof of concept already, and maybe more of a familiar name, I'd be less cynical. But the fact is nobody's seen a park like this before, and it's unlikely that the people who are going to want to go there will do so in favor of the greatest theme parks in the world just up the highway.
Look at it this way...theme parks work in a couple of different ways. You have your massive world-class theme parks. These are like Disney, and no matter where you build them (even in the middle of a swamp), people will come just because of the name. The Miami Wilds project has no such brand power.
Then you have theme parks like Universal and SeaWorld who have a great product, but not quite strong enough to draw people in from over the country. That's why these parks are placed in already-populated areas...to piggyback off the other attractions in the immediate area and prove that they have a great vacation-worthy destination. These places can ONLY thrive in the right type of market (for instance, Universal and SeaWorld and the other theme parks in Orlando work in conjunction with Disney World because there's NOT MUCH else to do in Central Florida...they round out a vacation). Miami Wilds would push the market into over-saturation. A point of diminishing returns, if you will--you put in one too many theme parks and it just gets in people's way, especially when it's a first-of-its-kind...not to mention the tourists who vacation in Orlando and who vacation in Miami are generally on two pretty different vacations.
Lastly you have regional amusement parks, relatively cheap, un-themed parks that thrive off of local business and day trips. Six Flags, Worlds of Fun, things like that. THIS, IMO, is something Miami could use. Because there are plenty of people who live there who would most likely attend this type of park, as well as plenty of tourists who would be interested in a cheaper amusement park experience. Where I can see many people coming to Miami but skipping out on this (probably expensive) high-end theme park in favor of Disney, there's not much of a comparison between a Six Flags and Magic Kingdom...there's enough differentiation to overcome the already crowded theme park market. A cheaper park would also rely less on tourism that can only be drawn from my first two examples. Another thing is that locals to Central/Southern Florida would be more likely to visit (and most importantly, REPEAT visit) a park that is very much unlike what they (we) already have (Disney, Universal, etc.).
Theme parks are a huge risk. I'm not going to pretend to know everything about the theme park business, and everything I've said in this thread is pure conjecture on my part. But let's just say that if I was Miami and was faced with this huge risk of building a multi-million dollar theme park that has no built-in brand name attached, these points are things I would heavily consider.