DACA does not expire in March because a Federal Judge issued a stay on his EO. DACA will stay in effect until new legislation or a Supreme Court decision upholds The President's right to end it. That decision will come down in April.
No doubt the Court will uphold Trump, but not until April.
DACA participants have to renew each 2 years or something like that. Even the 9th Circuit agreed that taking no new applicants is okay, so at this point the argument is over accepting renewals.