When the border wall finally goes up, illegal alien smugglers will take to the shores to bring in illegal aliens. We need a strong Coast Guard (as well as a sentry presence on the border wall) to secure our borders.
The wall is merely an impediment. We could end illegal immigrant trafficking faster by cracking down on illegal labor. Clear out all the people traffic and catching the remote cross border smuggling traffic becomes manageable. You are correct regarding smuggling enforcement being a game of wack-a-mole. A lot of dope traffic used to come by air and sea, as it will again if the land border ever tightens up.
As far as the $1.3 billion haircut, I don't know why or what the plan might be. USCG has had funding issues for a long time. Need to see Kelly's ideas on this first.