I'm just a bit concerned that the falling percentage, and falling numbers, of French participants might be reflected in volunteer numbers.
The best response to this if you're not riding is to volunteer. As the current Volunteers web page says
BE A VOLUNTEER AND LIVE INSIDE THIS GREAT EVENT
For how to apply, have a look at
https://www.paris-brest-paris.org/index2.php?lang=en&cat=organisation&page=appel_aux_benevols
That link illustrates some of the problems. It's only for Rambouillet, which is a wholly new control. It suggests contacting the other controls locally. Historically, those controls are managed by the local FFCT affiliated Cyclo-Sportif club. Their volunteer effort is a reflection of the active membership of previous years, and that component seemed to be getting older last time, as did French riders.
Among other trends are the decline of 'unofficial' controls. Gorron is an example. In 1999 they provided a village hall with beds, in 2003 a roadside feeding stall, in 2007 a welcome, with a bugler, and in 2011 and 2015, not much at all. In contrast, I encountered mobile support for the Thais at Brest in 2015, with food and drink.
There was a preference expressed in the 2015 Plaquette for a 'purer' unsupported approach. I can see the problems created by motor-home support cluttering the control towns, but they do take the load off the controls. UK clubs have provided support for riders in the past, Willesden certainly had a van in 2007, and Heather was essentially driving a VC 167 support vehicle in 2015, although its main use was as a base for filming.
One indication of the shortfall in expected volunteer numbers in 2015 was the sight of spectators at the roadside wearing volunteer shirts. The floating volunteers were handing them out from the little Citroens that they whizz about in.
I have floated the idea of 'all in' pricing with various French riders, and with the controller at Tinteniac, as handling payment seems to consume a lot of volunteer effort. But that seems to be a complete non-starter, possibly because French riders rely a lot on support outside the controls. That structure also makes club support more viable for 'etrangers'; the Thais commented that food was expensive in France, and unusual for them.
The volunteer structure as I see it is relatively accessible at Rambouillet, but the rest is de-centralised, apart from the ANEC motorcycle support, and a small group which monitors rule infringements, and tidies up the signage. The two approaches for those wanting to help would seem to be to plug into the PBP system, or to identify the potential gaps and provide direct support for specific clubs.
A volunteer thread is obviously needed.