I expect for most here, it's more want than need. Probably been a while since buying the last toy.I guess?
But real world impact: current ipad pro will run all ipad apps very well. you could be having the premium ipad experience TODAY, and for the next 6 months prior to the new ipad pro likely being released.
If you have an actual need for such a device, that's a long time to wait.
If you don't have a need for the device, don't buy it at all, and stop worrying when it will come out.
To be honest, barring RAM related inadequacies, I don't have any performance issues even with the 1st gen iPad Pros (A9X).
However, I enjoy reading rumors about the upcoming model. Not really worrying about when it will come out. Any of my current iPads more than serve my needs quite well. Would like 1TB, more RAM and 5G but it's not a burning need at the moment. I'm more than fine waiting whenever the new iPad is announced (and probably waiting some more for discounts if Apple increases prices again).