They can survive on their own, I would not and didn't look for a "dry" cow on my cow hunts. I shot the first one that gave me a shot. Looking for a dry cow is impossible while hunting. If multiple elk are running together, would love to know how you determine if a calf/calves belong to which cow...
When I was a kid, we had a whitetail doe hit in front of our house. She had a fawn with her and it was the middle of June. The fawn was only 2 weeks old. It survived all summer, we would see it in the yard/field on a regular basis. We finally lost track of it in the fall when it lost its spots and hooked up with some other does/fawns.
A species around today is alive due to its ability to survive. Killing a cow after the calf is 4-5 months old (basically a teenager) is not going to make a difference. Especially with a species that herds up like elk.
"Hunting is where you prove yourself"