This HAS to be for OC.
There's no way you could make him HC without having interviewed ANY other outside candidates for the job. It would just be irresponsible.
He hasn't interviewed Phillips, Turner, Rivera, either of the Ryans... anyone!
Now it could be that Jerry is going to hire him as OC, to get him in-house and beat the Dolphins deadline, and then, if he doesn't find anyone he likes better "promote" him in a week or two.
But there's NO WAY the announcement tomorrow can be for Head Coach. It would defy all business logic. And while Jerry may be eccentric, he's too good of a business man to do that.