My guess is, by the time they reach the border, the reduction in US aid will have been noticed in the Swiss accounts of Central American dictators and they will be shooting at the caravan marchers themselves.
many moons ago someone i know had a plan to stop illegal immigration..put 10 million dollars in trust for mexican generals and subtract a thousand dollars for everyone caught crossing the border- end of year tally up and start over ..it would take the generals about a week to stop the illegals from their side of the border...