It's hard to say whether Disney ever had any real intentions of continuing the TLK franchise...for one, any rumors I've heard appear to be tainted with fanon - "scripts" for a 4th TLK movie written by fans that are often confused with Disney canon.
For another, even if Disney DID have a TLK4 (or whatever) in the works, there's a good chance it was scrapped a long time ago when the Disney animated sequel machine was dismantled.
As far as I can tell, there is no current new TLK movie in production - not as a feature film, and not as a DtV, at least not before 2013. In all honesty though, I'm not a fan of the two sequels they gave us before and if they were going to make another TLK movie, I'd want them to sit down and think everything out (*cough*Kopa*cough*) before handing us something that may or may not make sense.
In shore, I want all of the TLK ducks in a row - I like fan conjecture and creativity as much as the next guy, but years of having fanon thrown in my face as being actual Disney "fact" is offensive to my thirst for actual canon truth/intent.