There were three episodes mentioned on the Star Wars blog that never aired, there was some footage released prior to Season 5 debuting which never aired (see below). There is also talk of some other material that was developed, and a promise by Dave Filoni himself that this missing Clone Wars material will somehow get into the hands of fans in 2014 still.
But, barring that bit of "extra" material coming out, out of order and out of context, no doubt, the Clone Wars is finished. It's all been aired, and it's all been released on home media, and I've now actually watched it all. While Star Wars: Rebels will no doubt fill much of the same shoes, it'll be different.
Of course, over the last few days, there have also been other big news items for Star Wars. The release date for Episode VII was issued (and it's not Memorial Day weekend, like normal, but is rather in December 2015.) And, Star Wars' facebook shared this link.. which doesn't actually say it's for Star Wars, but c'mon. I think we can all figure out that it is.
So it is the end of an era. But it's also an exciting time as the new era is peeking out through the curtains, letting us know that it's on its way too.