I'd quibble a bit (or a lot) over the notion that International Drive is Orlando's key tourist hub. It's certainly the big location
off Disney property. Of course, that's the Sentinel's particular bias - since they're writing for the local population, they like to maintain the illusion that Disney is not the center of Orlando's universe.
(I have a vivid fantasy image of what would happen to the rest of Orlando if Disney were ever to disappear - most of the city would gradually be sucked into the space vacated by WDW as if it were a 28,000 acre sinkhole or black hole.)
The wheel will probably pull well for the folks staying off Disney property in the International Drive/airport/convention center area, visiting Universal, attending events at the Convention Center, shopping Florida Mall, visiting friends/relatives in the area, etc., but unless they provide some sort of free/low-cost bus/shuttle service for Disney's on-property guests, they'll be losing out on a substantial chunk of business.
The notion of it being a point of orientation for visitors to Orlando (hitting the wheel before they decide where else to go) is a powerful concept if you assume people arrive in Orlando with no idea of what they'll do/where they'll go. I wonder just how many people fit that mold these days (driving through on I-4, stopping for a day or two on their way to/from other Florida destinations)?
For folks driving from the airport to I Drive, it'll be one huge "weenie"/tourist magnet. It's certainly not as likely to capture folks who rent a car at the airport and stay in Kissimmee - they'll probably be driving out on 417. Similar for folks taking DME or driving to WDW from the airport - they also often take 417. From 417 it'll just be a speck on the hazy horizon.
A 400-foot wheel is roughly twice as tall as the Contemporary. On a good day (clear, low-humidity) the view will be cool, but it's far enough from WDW property that if the viewing conditions are sub-optimal, views of Disney property will be very disappointing. While WDW looks really cool in Google Earth, during aircraft approach/take-off it doesn't look nearly as cool - each park looks like a small patch in a sea of green. While I love seeing all that green, the lakes, etc.,
I've been up in the London Eye, and as excellent as the views are, sights more than a couple of miles from the wheel are just too distant to be anything but background. If the Houses of Parliament/Big Ben, London Bridge, Tower Bridge, Tower of London, etc. weren't so close by, I'm not sure how compelling it would be.
Back in my days in radio engineering, I was a "regular" up in the Empire State Building (our FM transmitter and antenna facilities were on very high floors). Absolutely excellent views from around 1,000 feet (more than twice the height of the proposed wheel), but again, the best views were within a couple of miles. Beyond those distances, you really had to come at night, when the haze tended to disappear and the entire NY metro area became a carpet of sparkling lights. Based on what we see from the Contemporary and from aircraft approaches/takeoffs, I'm not so sure Orlando will be quite as captivating as New York at night.
I also wonder about such a structure in the "Lightning Capital of the World." How often would it have to close due to approaching thunderstorms? At its normal rotational speed, it could take a half-hour or more to clear the wheel of passengers. I enjoy extreme weather, and the view up in the clouds during a storm can be spectacular, but I suspect that, no matter how well they protect the wheel from lightning strikes (and it certainly can be done), the perception of danger would force them to evacuate the wheel in a storm. They don't have quite the same problem in London.
Observation towers/decks of this sort work really well in high-density urban areas. The Orlando area is much more spread out, so the viewing may not seem nearly as "rich."