I wish it did not have to end.(MAJOR SPOILERS Farseer & TM)

[Mervi]

Yeah, I've seen a few comments here and there, just pure speculation that this might be the case. I think most of it is based on Robin's comments after her long-time literary agent Ralph Vicinanza died last autumn.

I didn’t much like the last piece of advice he gave me. And I was putting off discussing it with him because, in retrospect, I already knew he was right and he would ‘win’ the discussion. Now I wish I’d called.

But, as I ended up doing with every piece of advice he gave me, I will be following it. More on that in a few months.

The speculation goes that the advice was to get back to the story that readers have been requesting so much, the Fitz&the Fool stuff. Given Robin's previous explanation why she hasn't written more about them (it can be found somewhere in the fanfic thread I think) this speculation certainly makes sense.
Also, there's this blog post on Suvudu that seems to hint that there's a F&F book in the works. (Scroll down until you see the bit about The Inheritance.) No idea where that info is coming from though (could be there's proof copies of the Inheritance around with a blurb about upcoming stuff, or maybe the writer just has inside information being some sort of an insider in the industry as far as I know).