The arrangements in 2015 were a bit of a one-off. The start/finish had been at a big gymnasium next to a large roundabout for a number of editions. There was a large campsite nearby until 2011, and many hotels in St Quentin-en-Yvelines.
So a routine had evolved. Finish, get some rest in the gymnasium, and sit on the roundabout, sometimes with a beer, and watch the big bulge of late arrivals come in. You got a token for a small beer at the end, and there was free food at the presentation for the podium places in the 'not a race'.
Two things happened to change that, the arrangements had to be more formal at the brand-new velodrome, and the safety concerns in France after terrorist attacks. So it's difficult to know what exactly will happen at Rambouillet. There are visitor facilities associated with the National Sheepfold, which is an historic breeding centre for the Rambouillet breed; a kind of Merino. There is also a UCPA (A government sponsored sports organisation) equestrian centre, which might have some sort of stadium facilities.
Those sheep and horse facilities might suggest some sort of stadium, with a show-ring, but it's hard to know at this stage. Security concerns might be less in a campus setting. The finish was a let-down in 2015, the actual route into St Quentin was a bit better than pre 2015. That was always a nasty shock if you finished at a busy time.
If they can organise a good atmosphere for the finish, then Rambouillet could be a lot better than St Quentin. One concern I have is that PBP is very close in time to Semaine Federale, and there's organisational overlap between those two large events. Time will tell.