There is no plug-and-play upgrade SKU that allows you to drop Rubin compute boards seamlessly into a Blackwell rack. A Blackwell NVL72 rack pulls around 100 kW to 140 kW. A Vera Rubin NVL72 rack is estimated to draw up to 190 kW to 230 kW per single rack. Rubin is also liquid-only cooling. Further it uses NVLink 6 which requires a different backplane.

Where is there evidence of buyback program for Blackwell boards?