The "re-run" of the Vercors event will be in the UK in 2016, so (he says with some trepidation) it's up to us to make it even better than the Vercors event. The Millau event is a French-national event that has volunteered to host the annual European get-together. This compares with the 2016 one which is a special one-off European event held every 8 years.
Whether that actually means the Millau event will be any smaller than the Vercors one remains to be seen, though. It also coincides with the 50th Anniversary of the FFS, so may well be a big one.