They are developing a Blue Water Navy.
Ironically, the true threat these pose might be to our Air Forces. Though probably suicidal, these ships can be sent out into the sea under the anticipated flight path of US air strike groups. With powerful SAMS (not ManPads) these things could pose threats to even the highest flying strike groups, especially AWACS and command aircraft.
That is a lot of missiles on one ship. By comparison, our newest Arleigh Burke class destroyers have 96 VLS launchers each (the older Burkes have 90 each). I have to wonder if China has closed the gap on our 1980s vintage Aegis Combat System technology, too. We shouldn't be surprised that the country that builds all of our computers is quickly catching up on high tech weaponry. We are swimming in China's lake, and we will have to fight them one day.
A missile barge? A cheap small way to saturate defenses?
Would not be surprised if this is another part of PRC area denial strategy.