That would be more meaningful if conservatives haven’t spent the last 40 years insisting that the problem isn’t immigration, it’s ILLEGAL immigration. Which, of course, is total nonsense.
The problem is that the USA is no longer American, just as the Mandate of Palestine is no longer Arab and the South African Republic is no longer Dutch. The answer, which I have been pointing out for literal decades, and which is still considered wildly beyond the pale by most liberals and conservatives alike, is to restore the pre-1965 national demographics, either repatriate those who arrived after 1965 and are descended from those who arrived after 1965 or give them their own sovereign part of the former USA, and prosecute every single individual who was responsible for opening the immigration process to the mass foreign invasion for treason.
Such policies are not politically viable now and it’s unlikely that they will be politically viable in the future. So, there will be war. It will be a stupid, terrible, and entirely unnecessary war, and the results will either be a) more or less the same as if the policies were enacted or b) considerably worse. Something resembling the partition of India, which involved 2 million dead and 20 million displaced, is the most likely outcome, only on an even larger scale.
It’s not enough to END both legal and illegal immigration. The effects have to be reversed if America is ever going to be anything resembling America again. Certainly there is room for some valued immigrants or descendants of immigrants, integration is real, possible, and often desirable in a small percentage of sufficiently compatible cases. But unfortunately, politics is a very crude and clumsy tool, and war is an even cruder and clumsier one.
So decline, fall, war, and partition is by far the higher probability outcome. As I have pointed out every now and then, where do you think homogeneous societies come from? They are born of heterogeneous empires and war.