My humble opinion is that a sequel to JJ2 is actually quite likely, there have been at least 3 official attempts at a sequal (read: ≥3 tries) - Unreal JJ3 still in unreleased alpha stage, JJ Advanced which sold ok for a gameboy game, and iPod JJ stick shooter demo which is on Youtube.

So in conclusion, I wouldn't blame Epic for not trying, because it's proven they have actually tried to make a cequel but haven't finished yet, released it on Gameboy Advance or resulted in only a gimmick (as in the case of an iPhone, iPod or iPad game).

I think to make a real JJ3, first have to come up with better marketing strategy such as stylize the product to something new like Dust: an Elsyian Tale. Like maybe since the JJ3 alpha was kind of unrecognizable to some, it could be for example JJ3: KRSplat Edition or JJ3: Skyward Sword. This is about brand name recognitipn and appeal to consumers. Furthermore we could spam the updates to JJ1, JJ2 and JJ3 which Epic might not even be aware of - otherwise it's impossible for them to create a game that would compete in fans' eyes because they have to know what we want in a game.

OpenJazz, JJ2+, patched JJ3d, JJ1 for Windows Phone - these are practically official releases to the community because they simply fix bugs and make necessary improvements. These are things that would teach Epic Megagames to learn from their mistakes! I wonder if Epic Games is aware of all the ports, remakes and patches to Jazz Jackrabbit games?