This is a very good take on where things stand. I would tend to agree with what is written in this link. Have a look and see if you agree:
TwitLonger — When you talk too much for Twitter
Guy has lot of things wrong in that tbh. Mixes release clause with buy-out and goes on about structuring of the deal when Griezmann if he indeed buys out his contract is required by spanish law to deposit the buy-out in full to spanish FA.
I also really doubt Athletico will negotiate. They were banking on getting replacements in and then they would most likely have agreed on a fee bit below the buy-out clause, but now I doubt there is another way of getting him then Griezmann himself triggering his buy-out clause.