I think you could get some back if you are a good responder to the big 3. I still see you have a nw3ish hairline, you are just very diffuse, and nw4 or so crown. I think I have also read that the diffuse can be fixed up with the big 3. If you thickened your diffuse you would be a Norwood 3-4 with a progressed crown which is right where a hair transplant could fix the rest.
This would be a lot of work, and you actually look good where you are, good shaved look. Up to you if its worth the time/cost.