I don't think that's a worry because they have systems in place to retain control of their territories by tipping off illegals and vote manipulation.    Conservatives don't outgrow democrats just from curbing immigration, democrats have to retain the group and wait for the illegals to keep reproducing by huge numbers and grow into more democrats.    They're resisting the wall because it'll reduce the deficit and prove Trump was correct.  Proving Trump right is how conservatives will outgrow democrats because it'll cause them to flip.