I think it's tough to get out of the usada deal now. It will give them a lot of bad publicity, and probably decrease the value.
In general I am all for WADAs work, But I am afraid they will break the UFC. MMA is different, And It is tough to walk into a cage without the confidence a little extra testosterone gives you. Random tests also makes it hard to recover from injuries, And In short time, stem cell therapy will also be on the list, And make 2-3 fights per year very difficult.
I think In a few years, they will be forced out of the deal, but I dont know how they would do it.