"They are trying to build a stable of programming that looks and feels like an HBO, a Showtime, like an AMC, like an FX. That's not an easy thing to do," he continued. "If they can do that, there's obviously a lot of long-term upside in the stock."
But Greenfield said, "We thought the stock had gotten relatively full. We recently downgraded it from a buy to neutral. I think it cools off for a little bit before it ultimately moves higher."
Going into the Emmys, there was a lot of speculation surrounding whether "House of Cards" would be the first series not shown on a broadcast or cable network to win best drama. That did not happen. Best drama went to AMC's "Breaking Bad," which is set to air its series finale next Sunday.
(Read more: Emmy awards: 'Breaking Bad' wins top prize)
"Other than a couple comedy awards, the entire show was dominated by cable brands and even online brands like Netflix," Greenfield said of the Emmy broadcast.
Ultimately, Netflix will raise prices," he predicted. "But I'd be surprised if it happened in the next couple of years."
"Keeping that price low—it's $7.99 [a month], effectively half of what HBO charges you on your cable bill—is a pretty compelling proposition for consumers, especially when it comes with this pretty robust kids' service that can act like a baby-sitter."
Not to mention viewers don't have to deal with commercials and they can stream programs anytime they want, he said.
—By CNBC's Matthew J. Belvedere. Follow him on Twitter
@Matt_SquawkCNBC. Wire services contributed to this report.