the Witcher 3 soundtrack is inferior to the previous ones AND ultimately inferior to everything Kirill did, especially with DOS.
I played Witcher 2, but my memory isn't good enough to comment. But I strongly disagree with you on the comparison to D:OS.
I am not a fan of the music from D:OS. I just think it's "good enough". In particular, the title screen music was nice, but it was too loud and powerful for the title screen and I didn't like it in context.
I don't agree with implications that Kirill is the best in the industry. Whoever replaces Kirill, I get the feeling that some people are going to hate on the new composer regardless of whether or not he does a good job. (I'm having flashbacks to when the lead singer Tarja left Nightwish.)