I always knew that PBP2015 would draw a line under Audax, hence my decision to ride to and from St Quentin, to make it a full-value experience, to "do it properly".
Although I had to pack on the return leg of PBP itself, the ride back home a couple of days later was the highlight of my cycling life. In fact my 2015 failure was a much nicer experience than my 2011 success.
I have shoulder/neck problems that have always meant 400/600/1200 Audax rides were a test of my ability to put up with neck pain more than my ability to pedal a long way.
It's hard to describe just how "not enjoyable" it is to deal with neck-pain right through the night(s) but it's not a cycling challenge in my opinion.
I may still do an occasional 200 (something I've been saying since I got back from PBP) but I'm more likely to save up my weekends in order to spend long weekends cycling between Cafes in Normandy and Brittany with friends, something I find hard to beat.
Having said all that, I did the same after PBP2011, when I felt that the PBP Audax "treadmill" had removed the joy from my cycling.
Audax, for me anyway, was about constantly proving to myself I could do it. I think I proved it. Now I'm just waiting for the ferry to St Malo in June.