·Time Warner Cable
·Verizon Online DSL
As Karl said, totally possible
Comcast will be pushing out Xfinity across their entire footprint in a year or two, though areas with FTTH will get it first. The result: 100M broadband speeds available to anyone in Comcast territory who is willing to pay for them. If Comcast buys other cable providers (TWC, parts of Charter) then you're already a long ways toward 100 million people with 100M available.
Cablevision already has 100M available if you're willing to spend $300 to set the service up (that's cheaper than the setup charge on some WISPs).
Insight will probably hit 100M when they launch DOCSIS 3 as well, which will also happen sooner than later.
Qwest and AT&T will be the big two providers who WON'T hit 100M any time soon. VDSL doesn't have what it takes. Windstream is in the same boat in most of their territory, except they're using ADSL2+ instead of VDSL. Frontier? Fuhgetaboudit. CenLink OTOH is rolling out fiber to compete with DOCSIS 3, so with a little pushing they'll hit 100Mbps without a problem.
FiOS, once it sees competition will hit 100M. Smaller fiber projects are either already at 100M or will get there with cheap bandwidth and/or competition.
The bottom line: 100M will be here sooner than you think for 1/3 of the nation. That said, there's a TON of people on older cable systems competing with standard DSL, so getting to 200 million on 100M will take a bit longer.