It would imply their extinction far into the future, after they've evolved to our level of intelligence, since our existence implies that the Great Filter exists ahead of us, not behind us
I don't think we know enough to say that for sure. If you are defining the great filter as the cause of the Fermi Paradox then it very well could be in our past. For example, the conditions or specific mutation that gave rise to multi-cellular life could be the great filter meaning that single celled life could be incredibly common but multicellular life might be almost entirely non-existent.
> the conditions or specific mutation that gave rise to multi-cellular life
Doubtful, given that we've been able to recreate multicellularity evolving in the lab. The initial jump to life, not so much.
We might want to say that our existence is some evidence that the filter is ahead of us but it could certainly be behind us (in which case the logic of the Great Filter doesn't apply for our civilization)
> Conversely wouldn’t imply the other life’s impending extinction symmetrically?
Yes and?
Just wanted to clarify that the implication arrow pointed both ways if it pointed one way, so I guess and that?