The existing CQB contains about 11000 questions and it took more than 11 years to get it to its current (not very high) standard. And for much of that time the UK CAA had 3 examiners contributing to (and sometimes hindering) the process. I believe that all of these posts have now been eliminated.
There is no realsitic possibility that a completely new CQB could be created for the new syllabus. Yes, there will be new questions covering the new subjects. Yes, some questions will have been moved from one exam to another to match the changed subject allocations. But the vast majority of the old questions will still be used.