Mike, team -1 have mentioned several times that the scan is 2k and only the newer prints and areas that needed re-scanning were scanned at 4k, the project is at 2k. Poita's scans, I believe, are all 4k (for the SW trilogy).
@lucasdroid - Mike's scans are for his personal usage and for use with Legacy, not for use by others in their film-based projects.