The 3090 will probably stay at a premium due to a few factors - I don't think ML performance plays into this at all though:
DLSS - There's a reason AMD cites "raster performance" since with DLSS enabled the 3090 has a major advantage.
AMD-specific optimizations - near the end of the presentation AMD disclosed that with all the optimizations on (including their proprietary cpu->gpu optimizations, only available on the latest gen cpus)- they could pass 3090's raster performance in some games.
I think for these two reasons, and the fact nvidia can't seem to get cards to vendors (and customers), there won't be a price drop on this SKU. They may however release a watered down version as a 3080ti and compete there.
[1] https://www.nvidia.com/content/dam/en-zz/Solutions/geforce/a... (Appendix A)
BTW - Whether it "could" be faster is indeed relevant because some of us are holding out for a Titan GPU next year with this unlocked. If you have unlimited budget or are under time constraints then by all means get the 3090, it is a beast. But if one has a 2080 TI then it's an important consideration.
If you can wait until next year you should always wait until next year, because there will (almost) always be something better than what is currently out. That's unrelated to whether or not the 3090 is good for doing ML research; it objectively is.