I answered "Create a new, awful tasting burger" to this question. Universal can market it as an awful burger six ways to Sunday, but as long as it's edible, people will go for it. "If you fry it, they will come."
I want an amazing burger for Krusty Burger. I want the best theme park counter service burger in the world.
Obviously, health warnings would need to be made extremely clear, but not everyone wants to go to Las Vegas, but at least once in their life, everyone wants a REAL burger!!
Correct me if I am wrong, what about a Alligator burger. It is different, the meat is in abundance, but a healthier option at the same time? Make it heart smart burger for a change?
One could be a standard burger (i.e something everyone could / would order)
The second could be the gross "novelty" burger. (For the fun people who would buy it just because)
There is a market for those who'd try it. For example, those Jones sodas like turkey & gravy & green bean casserole sell pretty well considering the contents.
And I don't necessarily think it has to be super unhealthy, just "gross". (random foods tossed together)
I also like Jeff's idea of copying the Heart Attack Grill, as long as they don't go and serve quadruple bypass equivalents to park guests (can't imagine that would sit too well after a spin on Transformers).
The thing is, though, that I'd wager 95% (or more) of the people who'd wander in there for a burger would never know that Krustyburgers are supposed to taste bad (like on the TV show). The Simpsons is only casual viewing for most people these days and few will know the minutia of the show's history. If something didn't happen last week and isn't covered in TMZ this morning then most people will not know about it.
An interesting thought for Krustyburgers is actually to make them vegetarian burgers...and not use any meet. That could be an interesting inside joke...and also a riff on the "Doublemeat Palace" burger from the old Buffy the Vampire Slayer episode (where the big secret that the burger place was hiding was actually that their burgers were made from soy and vegetables and no meat). A lot of people will think a vegetarian burger tastes weird and odd...but it is edible and a vegetarian option would be interesting for guests. The backstory could be that Krusty saves money by using only vegetarian patties and no meat in the restaurant but he lies to customers and tells them it's real meat. Maybe Homer could "expose" this to guests somehow (so that people are aware it's all vegetarian burgers inside).
I'm actually more interested in the "Flaming Moe's" drink I am sure they will make. Remember it's supposed to taste like cough syrup and have that fire element. Obviously, real flame cannot be used but maybe special cups could have flames on them? I think the cough syrup was purple so I always thought that the Flaming Moe would taste like grape. Lisa ordered a "Virgin Moe" in that episode so there was a nonalcoholic version. They will probably have it straight or frozen...maybe they will even just call it a Frozen Moe instead of a Flaming Moe.
I recommend calling them "Prion Burgers."
Krusty Burger should follow suit. Plenty of jokes about the food and service around the restaurant but a good actual product.