Sony is now said to have an upgrade for the Alpha 7R IV in the works. This alleged fith-gen model will still have a 61MP sensor and a 26MP APS-C crop; however, it is also projected to come with the BIONZ XR processor, improved PDAF and a potentially enhanced ISO range. Nevertheless, it is rumored to start at the same price as its predecessor.
https://www.notebookcheck.net/Sony-will-update-the-Alpha-7R-camera-series-with-a-newer-processor-and-more.537765.0.html