It's a difficult proposition as for fans its HUGE, but not for the rest of us. We can talk fanbase size, console sales etc till the cows come home, however are UOR really going to put this IP across two parks, will there really be a need?
I can see this being limited to Kidzone only. Will we see Potter size crowds on opening, I doubt it. The key to much of Potter's success is the age group, it spans generations, kids grew up with it, parents enjoyed it at the same time. Does Nintendo span generations, not really. If it's replacing Kidzone, they are gonna keep it very kid friendly, it'll be nice to see, but not something to rush out for. I think sometimes on the forums we forget we are forum geeks who like gaming, films, technology, Sci-Fi etc etc. Joey Public's parents (who Joey needs to visit this) are probably not and won't see it as a family thing that everyone can enjoy, but see it as somewhere to take the kids when they do the rest of UOR.