Does the footprint fossil disprove tiktaalik as an intermediate form between fish and tetrapods?
No it doesn’t. Tiktaalik is still an intermediate form between fish and tetrapods. All this suggests is that there may have been other transitional species as well. Nobody was eliminating that possibility. (Nobody was saying that tiktaalik was *THE* intermediate form between fish and tetrapods.) Tiktaalik lived about 375 million years ago. These footprints appear to be about 390 million years old. That’s *at most* about 15 to 18 million years older (not “at least”) … which is not that big a difference when we’re talking almost 400 million years ago. So if verified, would suggest that a slightly older species was also making the transition. That is not that surprising.
