What does this mean for the millions of RIVA based STB card owners? It is too soon too tell. It seems that 3Dfx made this move since STB has one of the largest manufacturing capacities for video cards.
They also were the premier nVidia OEM, the company that would be first to test and ship cards based on nVidia chips. This move may give 3Dfx the ability to build and market its own cards, without having to go trough another company.
Some 3D cards that are already made under this arrangement are based on the Matrox G200 and soon the ATI Rage 128. Matrox and Rage manufacture their own video cards, eliminating the need for someone to pickup their chip and integrate it into a card.
This may help 3Dfx control prices and release their own branded product. The extent to wich this will affect nVidia and STB card owners is still unknown...