For all that are saying this is Jason's last year and that he'll be fired after the season, read the tweet again... More specifically read the very last couple sentences... For the last time Jason Garrett isn't going anywhere.. Mark my words...
What?
The last few sentences say the opposite. It's Jerry leaving the door open that at the end of the year if things are bad, he can change his mind.
As others pointed out, if Jerry truly believed Garrett was one of the best coaches in football and would be highly sought after on the open market, then why not extend him now? For all intents and purposes, Garrett is a FA anyway after this season. Once that final second rolls off the Cowboys season, if Jerry doesn't sign him, Garrett's agent could put feelers out for other jobs.
So if Garrett truly is an elite coach, why not extend him now?
He's trying to sell his fans a steaming load of crap but few are buying it.