$3K per year per employee, but they probably pay close to that in the heal care benefits anyway.
Obama would love for employers to not offer any health insurance to their employees. It would be a major push for having a single payer plan, since so many people would be looking for health care, and with Obamacare, most of the insurance companies would be working with the government, anyway.
Other than the legislation being repealed by Congress, or being overturned by the Supremes, I don't know what else they can do except widespread refusal to participate, including refusal to pay fines or taxes. Then we'd see what the Federal Govt. would do.