It doesn't seem they are restricted to microtransactions only. From the other thread:
Yeah, I just saw that. Good news all around, false alarm.
The only only portion of MGS that I care about is MGO -- which I don't even know if that's still a thing or not... but I hope it is.
I'm really hopeful MGO isn't DOA. The sudden delay on 4 months for the PC version, ect, makes me nervous about any sort of long term support.