I took a closer look at what EKWB and Alphacool are doing and it really doesn't look good (not even for the 3080): EKWB completely changed the layout for their 3080/3090 models a few days after the first announcement. For questions about active backplates (or similar solutions) they only refer to their (very expensive) passive backplates.
Alphacool actually didn't really say anything about the VRAM on the 3090, but in such a strange way that you could almost think it only became clear to them after the question that this could be an issue: "And about the memory. .. One should not believe too much in the current speculation and discussions. It is down to the nature of the humans to make wild speculations, discussions and conjectures without a single fact on the table. This should be taken more as a sport than to be taken seriously. It won't take long anymore and the facts will be brought to the table. " (quote from an Q&A from their own Facebook page).
Of course, you can think about that what you want, but with 350W TDP and the measured values from Igor, I would currently think twice about that and better wait another 2-3 months for futher tests and better products and use the card under air in the meantime.