That isn’t guaranteed. Sony have reserved the stacked sensors to the A9 and A1 line so far and I fully expect Canon to do the same to differ the pro bodies from the R5 and R6. If you need blackout free, high FPS, and low latency; then go buy the R1 or R3. If you need a general do everything camera, buy the R5 or R6. Mirrorless bodies are differentiated in many more ways than we seen in DLSR, now the high end can have faster startup times, lower latency, no blackout, higher resolution and faster EVF’s, and gosh knows what else to differentiate them from the 5-series and 6-series.