So the fedural government will regulate?
No. As with the exchanges and the PCIPs, the feds will only do it if a state prefers not to. States have autonomy in enforcing this provision.
This proposed regulation does not establish a standard for unreasonableness that a State must use or apply; nor does it require a numerical standard to be applied under State law to determine whether a rate increase is unreasonable. Rather, a State regulator would apply the applicable standards that exist under State law.