I just got my Apple Watch 3 in May 2018 so it’s only been 4 months. I got it for $400 au with Apple care included. If I get Apple Watch 4 it would be like $780 with Apple care. Too much for upgrade, although I can probably sell mine for $400 I think if I keep it for two years and replace it for $99 I can keep it for total 4 years. By that time Apple Watch 7 or 8 might be out. Apple Watch 3 is fast enough for me. I don’t use sim either. Don’t really want big screen. So I might keep it as I am happy. If I upgrade will probably be because I found a nice and cheap Apple Watch 4/5/6/7 Like my iPhone 6s not xs, I keep it because it’s all I need. Works fine.