RTZ to Secret ? Hell yea! They've been teasing this for a while but nothing official yet but I must agree that Secret has a great team right now that won't need big modifications in order to chase that Aegis one more time but with RTZ on team , they will be better for sure. Now the big question is : Can RTZ perform in other team ? He has been with EG since 2015 if I remember correctly so it will be challenge for him no matter what team he will go to. 
There's the recent announcement of Team Secret and Nisha chose to be out of the team. So, if the rumor tends to be true and it is RTZ going to Team Secret, who's going to be playing as a carry and the mid?Who's better at mid, RTZ or Crystallis? But if it's about being carry then no doubt RTZ is the better guy.
I'm more into thinking that Team Secret is likely to fill the slot of Nisha either by Topson or by Boom, an ex-mid player of Gaimin Gladiators.