Wrong! The IS convertible
Wrong! The IS convertible will not transition into the RC. They are COMPLETELY separate vehicles. The RC is based on the GS platform that has been shortened. Put simply, the RC is its own platform, sharing the width of the GS but shorter than the IS. The only similarity shared between the IS and RC is the interior layout, and that is all. The interior will be roomier (wider) than the IS, which will be welcomed.
Bottom line: if you want to have an idea what sitting in the RC will be like, sit in a GS (to get a fell for the ineterior size) then close your eyes and picture an IS interior.