In the US, the RX 6800 has been in relatively short supply and the price has been significantly marked up for basically ever. At present, retail prices are roughly as follows:
RX 6700 XT: $500
RX 6750 XT: $550
RX 6800: $760
RX 6800 XT: $800
RX 6900 XT: $950
RX 6950 XT: $1,100 (but sold out everywhere)
In terms of performance, the RX 6800 is 25-30% faster than the RX 6700 XT, because it has 50% more CUs and 33% more memory and memory bandwidth. Again, if it were in stock at the $580 MSRP, it would be quite compelling, but when the 6800 XT is only $40 more it's the better choice: 5% more money for 15% more performance.
Based on sales on eBay, the RX 6700 XT has been one of AMD's most popular RDNA 2 GPUs. In the past year, nearly 10,000 have been sold on eBay, compared to only 2,250 RX 6800 cards, 3,700 RX 6800 XT cards, and 2,800 RX 6900 XT cards. The 6600 XT is catching up, having sold over 6,300 since launch, but it hasn't gotten there yet. I know eBay isn't the retail market, but that's as good as I can do with the data that's out there.
Alternatively, the Steam Hardware Survey (DirectX 12 API page) shows 0.30% for the RX 6600 XT, 0.25% for the 6700 XT, 0.15% for the 6900 XT and RX 6600, 0.13% for the RX 6800 XT, 0.09% on the 6500 XT, and 0.05% for the RX 6800. So in that case the 6600 XT has surpassed the 6700 XT in total sales to gamers, maybe.
I don't think AMD will totally halt RX 6800 sales, but it has always been a GPU that only exists to take care of yields. If a Navi 21 isn't at least 90% functional on the CUs, and fully functional on the cache and memory controllers, it can't be sold as a 6800 XT. I do wonder if some Navi 21 chips end up as RX 6700 / RX 6750 XT, just because there will inevitably be flaws in the Infinity Cache or memory controllers. But perhaps AMD just doesn't bother with such chips.