i only remarked on that particular expression
this one is legit, i feel like a closer translation would be what are we to do? despite the lack of Dative case
indeed this is a set pattern for a certain type of inеrrogative sentences like
куда нам бежать?
как мне быть?
когда ему прийти?
мне идти will sound normal in an alternative question like мне идти или бежать? or just in a simple question мне идти? which is basically asking for permission to go, but hardly as a statement