Individually, I believe. They’re already streaming on… whatever service Criterion works with, but they are getting everything set for physical releases.
I doubt the '54 film will get another release, as they’ve already released that, like you said. But I’m hoping the King Of The Monsters version will now be in equal quality.
Also, looks like it’s not just Godzilla, but other Showa era films like War of the Gargantuas (!!) and Rodan.

I would go for a re-relaes of G’54 with a cover matching the rest! I really dig the style.