The Panasonic Japan press release contained info about the GH7 production which is going to be 1,000 units per month.
Preorder links:
GH7 at Amazon, Bhphoto, Adorama, FotoErhardt, Calumet, WexUk.
XLR unit at Amazon, Bhphoto, Adorama, FotoErhardt, Calumet, WexUk.