I'm MODERATELY in favor of the wall.... but I doubt it will do much good.
The "draw" here is all the social goodies they get and jobs. Those who think their legal application for a visa will be denied (they are for criminals, rapists, child molesters, etc.) then they will avoid the normal process of applying at a US embassy or consulate - and will "crash" the boarder, entering illegally (at times, subjecting their family to this, as well). As long as they get all the freebies here and the jobs that are here, they will come. When the economy is good here, they come in large numbers.
SOMEHOW, we need to eliminate the jobs. If these ILLEGAL residents who felt they needed to avoid the normal process and the vetting it involved can make more money here than where they legally belong, they will come.... and stay. HOW to do that? I don't know. And can we NOT provide all the education, welfare, health care, etc. they receive as an award for being here illegally? Probably not. ER's are full of them. Schools are full of them. It's illegal to ask about their status in this country. I don't know what to do about that, either... we can't turn our back on those genuinely in need. Does the Federal government reimburse hospitals, schools, welfare agencies for supplying the help needed by people the Federal government is responsible for not allowing? Nope.
But as long as criminals can have a higher standard of living HERE - they will come. And since they don't give a rip about laws or governments or process, laws are going to be meaningless, process will be meaningless, walls won't mean much. And since (at least in California) they can register to vote (and tend to vote overwhelmingly for Democrats) the Democrats welcome them. So in "one party" States like California, where the Democrats rule unchallenged, there is a welcome mat.
I don't foresee anything happening.... except more and more criminals from other nations will come here. Wall or not.