According to latest rumors, the production of the Canon EOS 5DS and Canon EOS 5DS R has ended. Currently these cameras still in stock at most stores, but this series has definitely reached its end. There will be no DSLR replacement for either camera.
As rumored before, Canon EOS R3/R5S high-megapixel full frame mirrorless camera will be the replacement of EOS 5DS/5DS R. The release date for EOS R3/R5S is expected in late 2020. And latest rumors said EOS R3/R5S will feature with a 150MP full frame sensor, just take with a grain of salt.