They'd balk if you did that. But they could have been told "Create a wrapper API that adheres to this standard, or your product will not be available on the new national Healthcare site."

Most of the insurance companies would have scrambled to not be left out, because if they missed the Oct 1 date they could have lost out on a huge pool of new business for a year.

This wouldn't work for credit agencies and State systems, but that's a much smaller pool of systems to integrate with.