I don't have any confirmation yet, but we are certainly interested in seeing how popular this request is to know if it should be included.
In the meantime, you can still adjust the flow rate using the Communication tab on the machine control panel. For example, to change the flow to 120% of normal just enter:
M221 S120
If you want to go back to nominal 100% flow enter:
I'd say this is a highly necessary function that is used frequently in prepping models for production printing. Helps us to determine how hard we can push the printers to speed up jobs. I'm having to stick to V4 for now without this feature.
I used the Override settings quite a bit. For example, increasing the speed gradually to see if print quality suffered, and backing it off if I saw problems. Expecting people to type GCode into the Communication screen is a poor substitute.
The entire machine control panel was fully rebuilt for V5. So while this isn't there now, it's possible it could be added in the future. I can tell you we are definitely tracking the interest across several of these threads to plan future releases.