I doubt we will see a 5th gate until Disney addresses some of the issues in their current parks, in terms of more stuff needed in DAK, Epcot, and DHS. Once they get those issues addressed and if the DVC continues to expand and become profitable, then maybe they will look at a 5th gate. I think they they would also need to wait to see how some of the overseas Disneys do and maybe look at one for South America? (Assuming they create a princess born in the rain forest...lol).
Imagineers are paid to imagine, so I am sure there is concept art and rough ideas related to villains that could either become a park or a new land somewhere. The concept itself is actually solid if you truly think about it. I would assume that it would be marketed to families/individuals with older kids or no kids and would be more designed to go head to head against Universal. I doubt it would be be truly scary in the haunted house/halloween way.
But again, until Disney deals with Avtarland, possible SW and Carsland expansion I do not see another gate opening soon,
Totally agree! Also think that any new park will be totally linked to 1000's of new DVC Rooms. It just make sense from a business stand point.