In December 2019, shortly after the premiere of the first season of The Witcher, Mark Hamill said that he had not yet been offered to play Vesemir. Hissrich has already responded to this message from the same emoji as CDPR.
However, in a conversation with IGN, the showrunner was more verbose.
Mark has always been interesting to me and to the project itself. We have not yet contacted his agent, because while we are not looking for actors for this role, however, I like what is happening on the Internet and the reaction of fans.
We saw that the Witcher has a huge number of fans, and if you add fans to them Star wars. From this, my brain explodes a little.