Keep in mind that most people on this Forum have chronic pain, so our experiences may be somewhat skewed.
I do know people who have found either long term or permanent relief from a single epidural injection. Just because someone shows signs of disc disease does not mean they are consigned to a life of pain. Many people have no symptoms. Some will have a single episode. Others will suffer intermittent or even chronic pain.
I remember years back when I first got my orthotics (I had been walking around for months on 2 sprained ankles with no signs except that I kept falling down, even when standing still & my posture has suffered severely) I experienced a severe pain starting in my low back, shooting down my hip, my leg & all the way down to my heel. I got a single epidural in the office & was good to go for years and still don't experience that type of pain. Now I get epidurals on a more regular basis for a separate, unrelated condition, but there are definitely people who improve long term after just one and don't ever need to go back.
Hopefully, you will have a full recovery from the epidural. They are supposed to last several months, so if you follow your ortho's instructions for rest, ice/heat & PT/activity, there is a real chance your body can fully recover while the epidural is still working and that you won't need any further injections. Just take it one step at a time. If things continue to be bad, at that point you could look into daily medications or pain specialists. For now, just try to stay positive & follow your doc's post-injection instructions to the letter.
Best of luck next week!