From what I know, I don't think there will be any FW updates unless Dlink finds something or we find something that really effects the routers use.
Well, in that case, then I guess it will never be revisited.
I wish they would include IPv6 however it's on listed as supporting it on there web page.
If I understand correctly, it
could be corrected via firmware (If there is enough storage).
Most equipment would be IPv6 capable with a software or firmware update if the device has sufficient storage and memory space for the new IPv6 stack.
SOURCE: http://en.wikipedia.org/wiki/IPv6 (Under Hardware and embedded systems heading)
What are some know bugs? 
I came across a few in this thread: http://forums.dlink.com/index.php?topic=14410.0
And a flaw/bug that should be either removed or fixed (Email setting).
Overall, I don't have any major concerns/gripes. But, when a company uses their resources to continually improve on their firmware while the device is still being produced is good practice. I haven't come across a device that has flawless firmware.
