New admin. and guns in Parks rule
I'd agree with this assessment that the new Administration, even if it wanted to mess with the issue, will have to undertake a new rulemaking to overturn the rule allowing firearms in national parks and wildlife refuges. It's already past its effective date, and thus is binding. The ESA rulemaking I'm not sure about. Understand that a final rule has certain stages:
1) A signed version is delivered to the Federal Register.
2) The Register prints it, usually 1-3 days later.
3) It has an "effective date," usually 30 days later (at least when I was at Interior).
If I recall from my days as a GS-14, the rule becomes a binding agency decision at (1), delivery to the Register, not at (2), its printing. (3) just governs when it goes into effect, and represents a delay so that the public can learn of it and be expected to comply.