Secure the border, and the problem becomes very solvable. Fail to secure the border, and nothing anyone does will work.
Putting 6000 guardsmen on the border would do it; we've already seen how a couple hundred volunteers were able to secure long stretches of border simply by their presence. By simply doing what the volunteers did, which we already know will work, the border would be closed up tight as a drum.
The catch is, that isn't what the guard is going to do. They aren't going to patrol anything, they aren't going to guard anything. They are going to sit back at the office and do, what I'm not clear.
Which means, I can't help it, it looks a lot like an attempt to show an effort at the border, without actually closing it.
Furthermore, he tied sending the guard to a comprehensive solution, which makes me wonder if sending the guard has to wait for his "comprehensive" legislation. I'll be watching to see how this plays out, but it will become clear quickly if this is action or merely the appearance of action.
Close the border, and they can take all the time they need in congress to hatch their wonder-plan. But if they can't even close the border, I won't be inclined to believe anything they come up with.