I've got a 6 month old Cochin cockerel with a worse scissor-beak then that. The flock gets fermented feed and there's an open container of water in addition to the nipple waterers. He is doing fine with normal life quality. Grew at a normal rate. Was way too precocious with the roo behavior (overabundance of testosterone I think), but has settled into a role as a subordinate. I may have to grind a bit of his upper beak off soon as it's getting a little long, but it's a quick, easy procedure with the dremel.
I'd say that if your chick is smart enough to figure out how to use her bottom beak as a shovel, tossing her head back to swallow food/water, then she may live "normally". If she doesn't, you'll see a decline in quality of life and should cull.