If he meant to actually do it he would not announce it. The announcement is a heads-up to the feds to forbid him to do it while getting credit for the intention. If he meant to do it, and all the border governors should take real steps in spite of the feds, he would just send the Texas Rangers to the border and secure it.
He has already sent the Texas Rangers, Texas State Troopers, and some Texas National Guard troops. We’re spending $1.5 million per week on that effort over and above our $332 million biennial (2014-2015) budget for border security.
It was a statement in answer to a direct question from Glenn Beck. It was not an official announcement of his plan.
To your point though, it was a heads-up but of the form you suggest. Perry has been asking Obama to send the Texas National Guard under Title 32. He’s telling Obama that Texas is putting the legal pieces in place and prioritizing/planning border operations to send the Texas National Guard under state authority to secure the Texas border.
That's right, the "announcement" is an invitation that Obama forbid him from acting; that way he's off the hook.