I noticed and read that iCloud does not preserve People conformed. So, will Migration Assistant?
If you transfer a Photos Library to a new Mac with Migration Assistant, the Photos Library will contain the named faces.
But it would be more convenient to use the Setup Assistent - this is available when you first start up a new Mac, before you create a user account on the new Mac. If you then connect the old Mac or a Time Machine drive to the new mac and let the Setup Assistent transfer all user accounts, your Mac will start up from your old user accounts as it has been previously, and the Photos Library will work better, because there will be no file ownership problems. this will be more problematic, if you first create a new admin account and then use Migration Assistant. Youer old libraries will end up in a different account and it will be more trouble to inherit your old Time Machine backup.
The next version of MacOS - macOS High Sierra - will finally sync named faces with iCloud Photo Library to iCloud and between devices, see: macOS High Sierra Preview - Apple