This was a mistake in their wording, the next Subnautica will be like the others, they simple meant it will receive updates for a time after, just like the other ones did. There won't be any battle pass or mtx bullshit.
Edit, link: https://unknownworlds.com/subnautica/an-update-about-the-next-subnautica/
WanderingPoltergeist
dcpDarkMatter