Apparently Feige said there were only three movies coming out in 25, which all but admits Blade isn't happening next year.
Not only do I not think anything else could make Blade's slot, I don't even know if the Feb 2026 slot will happen. FF as is will be tight with just a year to film before release*, but it already has a script / director / cast / etc. (and presumably Marvel pre-vis work is pretty high on that list of prerequisites).
Out of all of the possible unscheduled options - Blade, Armor Wars (Don Cheadle's D+ show turned movie), Shang-Chi 2, Doctor Strange 3, and Spider-Man 4, only Shang-Chi has a director (the same as the first) at the moment, and none of them are known to have a finished script, much less a cast. And yes, while it sounds like in many productions Marvel gets the pre-vis (if not final fx) done then has the directors / cast adlib the scenes between those fight scenes, you still need to have some semblance of a plot done to know who's in those action scens to do that pre-vis.
*It wouldn't shock me if FF (and possibly Thunderbolts) slide one release slot later if Blade isn't happening.