I meant, and I think stated, top level, where they already use comms.......
And for a sub....AR with comms simply says "sub ref" when ball is dead, or, as will be the case, the 4th can.
And am sure each and every one of us has done that rolly spinny hand thing as referee, or at least seen it, that is used a grass roots for a sub.
When the sub is complete? The flag, without 4th man, is lowered before the sub procedure is complete, esp when AR is taking note of who is on/off.
Game should not restart until AR is back in position anyways.
There is nothing in the sub procedure that cannot be done without use of a flag.
cant recall the last time as referee I needed a raised flag to tell me there was about to be a sub. First, if you are aware, you can see things at the bench/player getting stripped/getting instructions etc.
Second, we have voices.."XXXXXX sub" shout from my NAR (with or without comms)
I serious cant recall a time I needed a raised flag to know a sub was happening, again picture scene, the ball out on the other side, the standside raises flag, but the thing that draws your attention to it (if you are not expecting it) (and you are looking at other AR) is, REF SUB ! a loud shout, coach, other players, your AR.....
The AR will eventually act the same as the trialed AAR.
Unfair to call it nonsense, as, neither you, me or anyone, knows what 5/10 years holds.