I wonder if oak aging Brett beers, sour or not, is a different think than oak aging regular beers. Perhaps some different long term outcomes are possible?
It should be quite different as Brett eats the cellulose of the wood. I am sure there are biotransforms occurring as well as the Brett further attacking dextrines and polyphenols. My saisons go into a barrel at 1.004 and usually out under .98. Taste as it ages and the variation is incredible.
I have some chips I used in one of my first Brett beers. Been saving them in a mason jar in the fridge. Some of the chips are now little more than sponges after two years.