I hope Trump doesn’t compromise on much to get the 5 billion for the wall. The wall is important, but it won’t end all our problems if we allow it to be bypassed with stupid legal immigration law. It’s debatable what’s worth compromising on, but I don’t think we should even consider compromise without funding for the entire border wall first.
The president can not make any law, including another new law to correct our stupid existing law of chain migration. Only constitutional power president has is to veto any law passed by congress. So only the congress can pass new laws to correct bad existing laws. And congress can override a veto with 2/3rd majority.
President Trump is fighting to not only curb illegals, he also is pushing to abolish chain migration in favor of merit based immigrants.
At the end of the day nothing much can change until voters elect congress critters whose first priority will be to protect citizens first.