From NBC News:
Buried in Obamacare regulations from July 2010 is an estimate that because of normal
turnover in the individual insurance market, “40 to 67 percent” of customers will not be able to keep their policy. And because many policies will have been changed since the key date, “the percentage of individual market policies losing grandfather status in a given year exceeds the 40 to 67 percent range.”
That means the administration knew that more than 40 to 67 percent of those in the individual market would not be able to keep their plans, even if they liked them.
Yet President Obama, who had promised in 2009, “if you like your health plan, you will be able to keep your health plan,” was still saying in 2012, “If [you] already have health insurance, you will keep your health insurance.”
From the Daily Beast:
Millions Must Change Insurance Plans
Despite assurances that those content with current insurance plans could keep them after Obamacare becomes law, an estimated 50 to 75 percent of those with individual health coverage will have to replace their polices—and the Obama administration has known for three years. Sources in the Affordable Care Act say many Americans will receive a "cancellation" notice due to their policies not meeting standards of the upcoming law. The original policy stipulated policies from March 23, 2010, and on would be honored, but tweaks by the Department of Health and Human Services amended it to mandate a cancellation if any part of the policy was significantly changed after that date.