Hi! I did feel that too but Taemin recently said that he didn't plan on retiring at 30 like what he said during WGM or on other shows. I think he didn't sign the contract because SM is just so bad at managing his career, same for Onew. So I feel like both of them will probably sign with another company. There already was rumours that Taemin was signing with Kany's agency, l don't know if that's true or not. But I'm pretty sure they are not retiring yet.
If they were retiring I think they would have prepared us for that, and Taemin and Onew are still on SM group contract so they are still part of SHINee group activity. I think the only reason why Key and Minho renewed their contract is because they had to do so in order for the group to keep existing as SHINee. Otherwise they might not be able to sign their own songs neither keep their group name.
But what you said might be true, we will have to wait and see for now. I want to believe that there still is hope for Taemin and Naeun. But with all the rumours around them and their "current bf and gf" I'm trying to stay neutral whatever happens. In the end their happiness is what matters the most!❤️