Yes, being in the Mystical Archive does not affect what formats it's legal in (except for historic on Magic Arena, since some of them will be new to historic, but not all of the cards in the Mystical Archive will be brought to Arena).
Minor correction: All of the cards will be coming to Arena for draft. A small number of them won't be legal in Historic for power level reasons.
Wizards Jay
Minor correction: All of the cards will be coming to Arena for draft. A small number of them won't be legal in Historic for power level reasons.