Rainbow has been dead for a long time. I assume you mean that Ronnie was that carried on the great Mk I Rainbow, and that with his passing, we will no longer hear it as it was originally intended.
Over the Rainbow is out there making music as "Rainbow," however I feel they are not much more than a glorified tribute band. I know that is harsh, however Ritchie is/was Rainbow. It was his band.
Has anyone seen OTR live? Are they decent? I like all incarnations of Rainbow, however it was the MK I line-up that was the best.