He's created a Woodward and Bernstein-ish reputation for himself due to the courage he's shown reporting these stories. I suspect that he'll be the first stop for anyone who has a potentially dangerous story to publish. Those also happen to be the most explosive and attention-getting.
This is actually entirely untrue. Greenwald was a prolific blogger far before the Snowden leak. In fact, I only found out, like, a couple of days ago that he was responsible for publicizing the Snowden leak.
I have one name for you: Bob Woodward. How many years since Watergate? And he's still there... a bit whored-out, yes, now mostly a megaphone for the rich and powerful class he belongs to... BUT he's still there, and doing fine, despite having a total of zero major scoops since 1973.
The bar for Greenwald is pretty low, in that sense. I'm sure he'll do just fine.
It's not clear what the "opportunity" Greenwald's been presented with is. It could be his own news agency or it could be something different. It's a bit premature to be dismissive.
He was well-known to anyone with an interest in privacy, pre-Snowden. Judging by the interest the subject of privacy gets on HN, more than 5% of HN readers are interested in it and knew about Greenwald pre-Snowden.
Whether he can handle leaks on his own, who knows. I'm sure WikiLeaks, who has some experience in dealing with leaks, wouldn't hesitate to assist him.
One way for him to take advantage of his current popularity (which he acquired through loyalty) would be to create a pastebin-like blog for classified sources and material. I wonder if this is among his intentions.
I suspect there's space in the news sphere for something with the transparency of wikileaks and the mainstream credibility of the guardian / al jazeera / NYT