I think it would depend on how long the player would be off the field. I think it would cut out unnecessary yellows i.e. mouthing off etc but I would be concerned it would take any tackles out of the game. I think as Rugby is already a physical game their yellows are for consistent high challenges, stamping etc so would a yellow now have to be more severe as the penalty for receiving one is (an orange card!)?
I am not convinced it would help at all.
I think there will be even more blatant trips and pull backs of the shirt when a player breaks free. Certainly worth doing that for 10 mins in the sin bin. Think refs would go for caution and the sin bin option rather than a red card.
Think the only way it might work if were to be you get a yellow card AND a trip to the sin bin for the cynical stuff. That would cut some of it all out. That and making it maybe just 4 yellows to receive a ban rather than 5.
I see they are also talking about maybe increasing the amount of subs.
Before long it will be 22 players, 11 on the field and 11 on the bench and 6 subs allowed.
That will slow the game down more. Always about 30 secs to a minute for every substitution made.