Will my Milanese band for my 38mm Watch fit a new 40mm watch

The Apple online store is now showing Milanese and other bands only for 40/44mm watches, then in the notes it indicates the 40mm is also compatible with 38mm cases. 40mm Milanese Loop - Apple. It is reasonable to suggest compatibility is likely to be two-way and your existing 38mm will work on a 40mm case.

Update from looking at the keynote replay. Accessories from earlier series WILL be compatible with Apple Watch Series 4.