Treating your hemlock trees may be a good option if you have a few select trees that you want to save. Treatments can be expensive, so this is more suitable for trees near your home or cabin than in the woods. Contact an arborist to discuss treatment options.
Dying trees don't mean the end of your forest as long as there are baby trees to replace them. Installing a deer fence is a good way to prevent deer from eating the seedlings that will become your future forest.