I read somewhere that the new HMG might be a two barrel 14.5mm turret.Do we have any better pictures? From that image, it’s hard to tell what is mounted, but in general outline, it does not look much, if any, smaller than the 30mm.
The 30mm is in a mini-turret, there are additional mounting points for HMG, so it would not make much sense to sacrifice the 30mm for HMGs that they could have mounted in any case.
Additionally, HMGs are typically not mounted unless they are being used, so that makes me question the claim that the 30mm has been replaced.
The Navy does have a two barrel 14.5mm turret in service, specifically the QJG-02, but it is quite old and I believe there is a modernized variant of it which exists and was installed on the PLAA's new LSM ship from a few years ago however I haven't found good pictures of the turret.
Obviously as of yet we don't know if the 056's 30mm replacement turrets are twin barrel or single barrel, however the twin barrel variety has been observed in the "close anti surface gun" role for a variety of PLA small ships like LSMs, LCTs etc.
A twin barrel 14.5mm gun replacing a 30mm gun would not be a bad trade.
this is an image of the old dual barrel 14.5mm naval turret, used on older LCTs and older small landing craft. I believe there is a newer variant with a more enclosed turret but I can't find any good pictures of it.
The PLAA's LSM launched a few years ago was installed with the new turret.