Okay, just did some reading up on this... Source:
Search Results - THOMAS (Library of Congress)
I was correct in that the new law only applies to employer sponsored group health plans. This will not impact Medicare or any publicly funded coverage. It also doesn't impact anyone who has their own individual plan they purchase directly from an insurance company. Since the new law amends ERISA, I don't think it impacts any ERISA exempt plans either. ERISA exempt plans would be smaller employer plans that are fully funded (as opposed to self-funded). Other ERISA exempt plans include certain religious organizations and any tribal organization protected by a sovereinghty treaty.
The one interesting piece I noticed is a cost exemption. If, after the first full plan year of this change in coverage, a plan can demonstrate a cost increase of 2% or greater, they can apply for an exemption. Once the exemption is granted, plans may reapply for subsequent exemptions.
In other words, if this new law costs plans too much, they can go back to their old coverage.
Also, this new law doesn't require any plan to offer mental health coverage. Those plans that offer limited coverage right now may elect to exclude all mental health treatment entirely under the new law.