I am anxiously waiting, too. My 2.5 year old still hasn't gotten a haircut because I keep holding out (even then, we won't be trimming much as he doesn't really "need" a big cut yet).
My DH walked in several times in years past for a cut! My guess is the pent-up demand will cause them to use just reservations for awhile but once that evens out, maybe go back to allowing them on a limited basis. Who knows!
With the current phone wait times, I am just hopeful the reservation system will be online once it does reopen!