It's never as simple as that. Any discount cuts into the profitability of the product. Let's say a hamburger costs $10, of which $5 goes to cover Disney's costs (materials, labor, utilities, etc) and the other $5 is profit. With a 20% discount, it still costs Disney $5 to prepare the item but their profit falls to just $3.
At full price, sell 1000 hamburgers and you've made $5000 profit. With a discount, you now need to sell 1666 hamburgers just to net the same profits.
(All fictitious numbers, of course, but illustration is valid. Discounts do tend to increase sales, but question is whether that increase is sufficient to cover the reduction in profit.)
Disney is counting on Pandora to increase attendance. With Pandora opening at end of May, they've already committed to running the anniversary discounts thru first 4 months of that post-opening period. I think they'll be very cautious about going beyond that. Ideally (in their minds), Pandora alone will cause a traffic boost and they can start to ease back on discount programs. But we'll have to wait and see how it plays out.