AMD has promised to release more Navi 21-based reference cards throughout Q1 2021, according to a Senior Director of the company. It remains to be seen how many reference cards will hit the market though, but AMD feels that stock difficulties will stay until at least the second half of 2021. Hence, any reference cards sold this quarter will probably be resold almost instantly at a hefty premium.
https://www.notebookcheck.net/AMD-pledges-to-re-stock-Radeon-RX-6800-RX-6800-XT-and-RX-6900-XT-reference-cards-this-quarter.518023.0.html