That’s a real possibility, some analysts say today — and appears to be one reason for the 4.5% drop in Netflix’s share price in early trading. There’s a target on the streaming video service’s back following the U.S. Court of Appeals decision yesterday to remand the FCC’s net neutrality rules because Netflix is the leader in using the cable-dominated broadband system to compete with cable TV. It accounted for 31.6% of all downstream traffic in North America during peak periods in late 2013 according to research firm Sandvine. It’s “an important risk Netflix faces [that’s] often overlooked by investors,” says Bernstein Research’s Carlos Kirjner, a bear on the company’s stock. Another skeptic, Wedbush Securities’ Michael Pachter, says that cable operators might now feel emboldened to throttle Netflix subscribers’ broadband usage “unless they pay for unrestricted delivery.” He envisions a system where they’d charge Netflix a penny for every GB of data its customers use each month after they watch the equivalent of 40 hours of video. Netflix could pass that additional cost along to subscribers, probably raising the $7.99 monthly rate by $1. Or it could swallow the expense which, at about $360M, could “wipe out 2/3 of their profits.” Netflix likely would launch a PR campaign to portray the change “as the work of ‘greedy’ ISPs,” Pachter says. (Comcast would be an exception, at least for now: It agreed to follow the FCC’s net neutrality rules through 2018 to win the agency’s approval for it to buy NBCUniversal in 2011.) Another possibility, raised by Guggenheim Securities’ Paul Gallant, is a special charge for Netflix and others including Amazon and Google that want to stream potentially bandwidth hogging 4K video.

But BTIG’s Richard Greenfield — a Netflix fan — says not to worry: Cable operators depend on revenues from broadband, and Netflix is a big attraction. If they charge an extra transmission fee, and Netflix refuses to pay, “the ISP ends up hurting its own customers and discouraging those subscribers from using the service that is driving them to pay for faster broadband speed tiers in the first place. Great way to drive [average revenue per user] down!” And it would be a PR disaster. Consumers “might shift to other ISPs and/or complain to Congress. In the end, discriminatory behavior appears self-defeating and is likely to lead to harsh government regulation.”