Washington Examiner is usually a good source. This is a rehash of a Salon.com article (IIRC).
The slowdown in illegal immigration is because the economic benefits aren’t as good as they were in 2006. When things get better, it will start up again in force.
On the other hand, even if it’s true right now, it will be a lot easier to send the ones who are here back south. And with a wall, we won’t have a repeat of the results of Reagan’s mistake when the economy improves.
There is no slowdown.