Lots of thoughts on how Disney would benefit from such data mining, both as it pertains to each individual guest and as part of a large mass of people moving around their property.
INDIVIDUAL:
Most visitors already "voluntarily" give Disney tons of personal information when they check in, buy tickets, or sign into their websites (like for wifi use): name, home address, email address, IP address, family makeup, and travel companions. Although you may not give your specific income, Disney can make some broad generalizations based on resort choice, reservation types, and certain purchases (and I imagine there is a chance that DVC and Disney credit card members may have also given the company specific income information).
The question is how Disney plans to benefit by combining the INDIVIDUAL's information they've already handed over with their movements on the property using RFID.
The most obvious benefit seems to be selling that info to other companies. Similar info is bought and sold all the time, so Disney would be no different. (And Disney "selling" this info could be in the form of selling an attraction sponsorship. "If Company X builds this attraction, we'll give them the visitor data." You'd be amazed at how that is already in play at Test Track)
In most cases, that selling of info (and Disney's direct collection and ability to use it themselves) will lead to targeted advertising. Is that a good or bad thing? There's always the concern of email spam and junk mail (which can often be opted out, if a company has any PR sense). The other side of it is that the advertising individuals will see (web banner ads, Facebook, coupon offers, recommended products on websites, etc) will be tailored to their interests ("if I'm going to be exposed to ads anyway, might as well be for things I'm interested in")
By adding the RFID tracking component, Disney (and their partners) get a better sense of exactly how much you spend and what you spend your money at Disney on since every purchase can be tracked and analyzed ("Bill Jones from Vermont doesn't spend much for hotel rooms but likes fine wines").
But I'm struggling to see how else Disney or anyone else benefits by knowing where I am at any given moment on their property as an INDIVIDUAL. Where I think the tracking most benefits Disney is by monitoring all park guests as a group.
GROUP:
By combining the info visitors voluntarily give Disney (address/hometown, general income, etc) with their movements around property, I think Disney stands to gain a tremendous amount of info.
The questions it can answer are almost limitless. Where do the big spenders eat and shop? What products are of most interest in international visitors? Which resort are guests more likely to return to for a mid-afternoon swim? Do most visitors enter Adventureland from the hub or Caribbean Plaza, and do they stop at the merchandise carts there if they've already been to the Emporium?
Such info could potentially help Disney save money or spend it more wisely by allocating resources (like staffing or maintenance) differently. It could also lead to improved profitability with better product display placement (which is already a science in the retail industry, dating back to the people who decided it was best to put milk at the back of a grocery store). Will that mean more stores packed with the same generic merchandise or a different variety? It appears future guest traffic and spending patterns will give us the answer.
Disney could certainly use the RFID tracking to recruit sponsorships by showing the precise demographics that visit.
SELLING THE TECHNOLOGY:
Spirit's update seemed to suggest Disney was willing to sell the technology (which may be how they plan to recoup most of the $2 Billion). I'm trying to predict who those customers would be. Cruise ships and other large resorts seem the most obvious, since they would mirror Disney's business. But who else? Embedding RFID in a Walmart "customer appreciation" to show how different types of people move through the store?