No.
There are sites that are too large (StackOverflow) or too small (some of the recent Area 51 graduates and some others). Too large and it will be hard to manage - but some may get split and move here anyway. Too small and without the benefit of Google-ness, it will be hard to get a vibrant site with just ‘x’ % of a site’s users moving over.
The most likely sites to move first will be ones where the existing/former moderators or key top users have already expressed interest. Some sites have core groups of people both asking & answering - those sites will have more traction to get started than sites where most of the questions come from random people who ask one question and (mostly) never show up again.
While I expect that most of the initial communities will be direct transplants from SE, over time I would hope Codidact will evolve in a more useful manner.