When I decided to go natural, I had a bit of heat damage already and my bff who had all natural hair had a lot of heat damage from salon visits where the blow drier was always used on our hair and held so close to our hair that we see steam, smoke, whatever it's called (I'll add that I haven't used heat on my hair in almost a year now).
Anyways, as my natural hair grew, the heat damaged bits didn't fall of at first, but eventually, they did. Where your healthy hair and the heat damaged hair meets is a weak point so over time, that point would weaken some more and the damaged hair would fall off by itself.
Right now, I don't know if the ends of my hair (a little less than an inch) are heat damaged or just relaxed. I know most of it is relaxed. I never cut my relaxed hair, neither did I cut my heat damaged hair. I long-transitioned so, as my natural curls were growing out, slowly, like once or twice a month (after some time of growing my natural hair out), I noticed that I'll get quite a bit of hair when I wash or detangle my hair. That used to worry me till I actually held some of the hair and looked at it carefully. Then, I noticed that indeed it was relaxed and heat damaged. I mentioned that I have a little less than an inch of relaxed hair left, right, well, my hair was, well, about a bit less than shoulder length before I decided to go natural, something happened, yeah, err...a lady at the salon cut my extensions without asking (got yelled at by her boss) and in the process she cut my hair.I might add that she was a new worker there. So, anyways, my hair was about mid-neck long. Right now, it's a little lower than my collarbone and I have little relaxed/heat damaged hair left...why?....because they broke off by themselves.
Also, you can partially reverse heat damage by using 100% natural aloe vera on your hair (I use aloe vera gel straight from the plant). Also, I hear that protein treatments help too. I've had protein treatments, but I didn't do them for that reason and I don't think they helped much (or maybe you just get long-term results). Anyways, aloe vera gel may dry your hair out a bit, so, just to be cautious, get some shea butter on your hair then get the aloe vera gel on your hair too. Deep conditioning your hair at least once a week or once every two weeks would help too. Also, it would strengthen your natural hair.
You don't have to cut your hair, I didn't cut mine. I can't imagine myself having hair shorter than this again. I am going to get a trim in June, if I haven't lost all my damaged ends by then, but that's it.
So, just treat your hair right, keep it healthy, you won't have to cut your hair, all you have to do is let it be and the damaged ends'll fall off by themselves. Also, figure out ways to style your hair especially because of the two very different textures (the natural curl and the heat damaged ones).
Hope I could help.