Thank you to all that responded. leonard-p pointed me to the latest version of MPC-HC which is currently supported, so from my point of view, this matter has a happy ending. I'll continue to use MPC-HC.
I retract my comment that VLC didn't play the file, it seems to play the file fine.
I've also downloaded PotPlayer as suggested by use-erbrich, I haven't tried it yet.
I would rather call this an archive format instead of a delivery format. Your bpp indicates it will play beautifully using XAVC-S at around 60 Mbps. Should do fine on other folks' systems and players, too.