Most are illiterate and cannot even speak English. Many are criminals. Even if the premise is true - the US needs more young workers, which I don’t believe, we don’t need any unskilled, illiterate, non-English speakers.
Kick them all out - every last one. Then, re-create the merit system and only let in those with skills, capabilities and truly wanting to be American.
Hell most of the Mexican illegals are illiterate in their own language, much less learning English.
I was watching some “boo hoo sob” news report recently about a poor Mexican caught driving illegally getting deported and every member of his family couldn’t speak English except for the youngest children. The man had lived here 18 years!