As is usually the case, those who really know (being bound by non-disclosure agreements) are unlikely to say, and those who say are unlikely to really know. But going by basic info:
* Canon Pro-4100, introduced October 2019, replacing Pro-4000 introduced 2016;
* Epson P9570, introduced October 2019, arguably replacing P9000 introduced 2015 and P10000 introduced 2016; and
* HP Z9+, introduced May 2018, replacing Z3200 introduced 2008.
So by the standard of historical model cycles of this class of printers, there's no reason to think a new model is imminent, and indeed, even the oldest of them is not (until May) "a few years old" and the others are well short of that.