Oh, you can easily live without it!
The acid blend gives it a nice balanced taste, but the concord grape juice is acidic enough on its own. The pectic enzyme simply breaks down the pectin to reduce haze.
Make it with what you have. In two weeks or before bottling, you taste it and it tastes "meh" you can add some acid blend, or a little lemon juice for some acid. You can add the pectic enzyme if you need it to help clear, but you probably won't even miss it!