Trump’s wall will happen. Perhaps there will be open areas that will not be easy to build on, but those areas will be better patrolled. Trump WILL stop much of the problem. Trump WILL build that wall.
Cut off federal funds to sanctuary cities & states like Calif which allow illegals to have driver licenses. Enforce employer penalties for non-SS compliance via e-verify. Eliminate funding for schools that allow enrollment of illegals. Terminate welfare and other support for illegals. Arrest & deport those with visa over stays.
Just these measures alone will create a flow of illegals out of the country, and make other potential violators think twice about breaking the law.
It is the flagrant disregard for law that leads to the situation we have at hand. Serious enforcement of the endless multitude of existing immigration laws is all that is really required.