A new report suggests that the Xiaomi Mi Max 3 will have 2 successors: the Mi Max 4 and a Pro variant of the same. Both of these will have a 7.2-inch display and 48MP rear camera sensors. The Mi Max 4 Pro may have an in-display fingerprint sensor and a slightly better processor.
https://www.notebookcheck.net/Xiaomi-Mi-Max-4-and-4-Pro-specs-detailed-in-new-leak.402581.0.html