A Memory of Light is now out, but already the question has been asked if this is truly the end, or if there will be further instalments/expansions of the series. Brandon Sanderson has addressed this issue in both a blog entry and also an interview on Wired.com. Here's a brief summary of what the situation is:
During the writing of Knife of Dreams (2002-05), Robert Jordan revealed that he had come up with an idea for what he called some 'outrigger' stories. These stories would not be direct sequels to or extension of The Wheel of Time but would expand on some characters and feature side-storylines that would not be addressed in the main series. The storylines for the outriggers were not revealed at the time, although there was some fan speculation that elements such as Talmanes and the Band of the Red Hand's adventures whilst employed by King Roedran of Murandy (in the several months between The Path of Daggers and Knife of Dreams) would be suitable for exploration.
Later on Jordan confirmed that one of the outriggers would focus on Mat Cauthon and Tuon returning to the Seanchan home continent to stabilise the Empire and assert Tuon's rule there. This story would take place about ten years after the main Wheel of Time series. Initially it appeared this would just be one book, but in recent years Team Jordan have indicated there was enough scope for a trilogy. However, it has also been revealed that Robert Jordan himself only wrote two sentences of notes for the books, clearly not enough to base anything solid on. As a result, despite some initial musings by Tor Books and by Team Jordan, the outriggers will now not be written for a dearth of Jordan-written material and a reluctance to turn the series into an open world franchise.
When Robert Jordan expanded New Spring into a novel, he also revealed plans for two other short prequel novels. One would focus on Tam al'Thor, and the other on Moiraine and Lan's continuing adventures, ending immediately where The Eye of the World begins. However, Jordan again apparently did not write much in the way of notes for these books and again, they will now not be written.
Work on The Wheel of Time Encyclopedia is well underway. This book is being written by Harriet McDougal and other members of Team Jordan (Robert Jordan's assistants) and will feature extensive new information on the series. Early reports indicated that the book will feature a 10,000-word vocabulary for the Old Tongue and might feature new maps and tons of notes on characters, places and events. The book will be illustrated, but should not be expected before 2014 at the earliest.
The long-gestating and highly ill-advised Wheel of Time movie project is apparently still percolating at Universal Studios as it has done for the last few years, with no sign of any movement on it. The new Wheel of Time RPG appears to be effectively cancelled, with Red Eagle failing to raise any money for it from publishers and Obsidian Entertainment (the superb game development studio that had originally been hired to work on it if the money had been raised) moving onto other projects. It's possible that the completion of the series will spark renewed interest from those quarters, but at the moment there is no news on them.