As much as SM drives me crazy, I think EXO will renew, but I think they will fight hard (and validly) for a contract that is more beneficial to them, as well as perhaps carving their own label out like SuJu to have better control of their decisions.
For NCT, I think they will think long and hard about where they go and potential next steps, especially the original members, who remember Hansol (yes that was at the start of their career but still).
I think the members most likely to move will be either those that are kind of over idol life and want to strike out differently (maybe Jaemin or Chenle), as well as those that get poached by another company that is familiar with SM. (I'm thinking quite specifically of Lay's company. I don't think he'll renew with SM, but I do think he'll be watching the Weishens closely as they promote in China, as well as Renjun.)
I don't think Ten is going anywhere - he is tremendously talented, yes, but he also is in group that's pretty specifically built to maximize his strengths and give him greater opportunities.