DOJ has jurisdiction over a fairly narrow set of issues though, like bribery/FCPA and criminal matters. That's good but it would take the FTC to break up a hospital system or HMO, and that would take an act by congress and/or a better SCOTUS.

The state could pass more regulations regarding hospitals, as long as it's not preempted. But state anti trust law is complicated in that some things would preempted and some would not, but either way, I don't imagine new laws passing a divided state legislature that does very little except at budget time. PA anti trust law is generally aimed at gas station price fixing, resale price maintenance, bid rigging for state contracts -- not at big stuff that the feds handle like corporate mergers.