I think that the system mesh avatars will forever be a thing. That is inevitable. I still enjoy them at times, but I've since updated to my new mesh self, and I don't see me going back now.
It is hard to adjust at first, and I honestly question how I got to where I am. But I love my sexy mesh. I have invested in two mesh bodies, three heads, and I have slink hands and feet just in case, haha.
I feel that the system avatars will still be around, but most are updating to mesh to save their social rep, as you put it.