Certainly Bandwidth limitations are becoming a problem for broadband internet providers, who increasingly see customers looking to use the Internet for Streaming and downloading video, sometimes in high definition, and often during peak internet usage hours. At the same time companies like Verizon and AT&T are building data networks from the ground up which offer some consumers speeds slightly higher than what the DOCSIS 1.1 or 2.0 standards allow. DOCSIS 3.0 allows for much higher speeds, as well as IPv6 network management support.
Of course speed doesn't exist in a vacuum. Accordig to Gartner analyst Patti Reali "Cable's got to be ready with a [comparable] product that's not going to break the bank."
Unfortunately in some areas this isn't necessarily possible. One limitation of cable internet is its reliance on a carrying many subscribers' data on the same cable. While this is highly efficient for delivering video services where identical data is transmitted to every customer, it can severely limit individual users' throughput in areas with high population density.
Cable companies also have to worry about video services like AT&T's U-verse, which threaten to compete with cable television, giving current cable internet customers another reason to consider switching.
DOCSIS 3.0 technology should be ready for deployment some time next year. Expect to see it deployed first in areas where Verizon or AT&T have entered the market with their fiber optic networks.
Source: Ars Technica