Some answers from Maciej and Marek, taken from Polygamia(my rough quick translation):
Marek Ziemak's part:
Why did you decide to leave CDPR?
What is it that you will be doing at 11 bit studios? Is it going to be a bigger game than what the studio made so far?
You're abandoningThe Witcher 3 at the end of the production process, right before the release. Don't you regret it?
Maciej Szcześnik: Witcher 3 is going to be the best of the series, so fans can stay calm. Design is already finished and work is going full steam. CDPR is full of talented people and that will make the game successful. My decision to change studios in the middle of the project was very difficult to make, but together with colleagues from CDPR we took care about my leave not affecting the quality. I worked on the Witcher series for 10 years and wanted to take on new challenges for quite a long time. 11 bit studios offered me working on games that I wanted to work on for some time now. I am a fan of independent productions and that's what I will be working on now. I will also have an opportunity to work on games from beginning to end and be able to influence all of their aspects. It will let me to realize my potential to a greater extent and work on games from other genres. I hope you will like them!
Marek Ziemak's part:
Why did you decide to leave CDPR?
MZ: There were lots of professional and personal factors. Makind such a decision was of course very difficult and cost me a few sleepless nights. In the end the comfort of working in a company that I grew up in and that I know quite well lost with temptation of starting a new adventure, in a new environment and based on new rules. Besides, makind indie games - which I will be doing now - is interesting for me both as a player and as a game producer. Development of such games is based on different rules than making AAA games and I want to try that. I believe that the experience I will gain in my new position will let me develop new skills and look at game development process from a different, more global perspective.
What is it that you will be doing at 11 bit studios? Is it going to be a bigger game than what the studio made so far?
MZ: We won't be making a huge AAA shooter for sure. The way I see it, the scale of the game is not defined by the number of people working on it, but the number of people it can enchant with it's world. That's why both The Witcher and Prison Architect are big games. What I'm working on at 11 bit studios has a great potential
You're abandoningThe Witcher 3 at the end of the production process, right before the release. Don't you regret it?
MZ: I don't want to consider this as abandoning anything. My adventure with Witcher games took a long time(since 2006). I think it was a period of hard work, that let me learn and achieve a lot. I'm leaving The Witcher 3 project after 2 years of intense development at a stage I feel comfortable with and that will not hurt the end of the project. Our decision was not a surprise to the company and the exact date of our leave resulted from development schedules and time we needed to pass on responsibilities to our colleagues. I don't regret it. Though I won't be @ CDPR on the day of release, I still feel as a co-author and I will have personal relationships with many members of the dev team. I am extremely happy that I had an opportunity to be a part of this talented team and that I will use this experience I gained in my future career.