You wouldnt get 5v4, you dont often get 13 cautions in a game let alone in an overlapping 10 minute period.
You would get a lot of periods of shorthanded play… 11 v 10 etc. The issue there is that as we see when players are sent off ‘it ruined the game’ because the shorthanded team just park the bus and are very good at defending for long periods; 10 mins would be easy. Now repeat that several times…..
There is now a panel that reviews offences after the game, so diving cheats should start to be retrospectively weeded out. While a 20s review sounds good in theory; the problem I’d see there is that it’s often not clearcut (unlike in the gif above). You see it on MotD all the time, 3 ex players split….. ‘there was clear contact’ ‘yes but only because he left a leg dangling to get that contact’ ‘in any case he went down far too easily, just looking for a penalty’…….. to make it one person’s opinion in 20s to avoid disrupting the flow of the game which is one of it’s strengths, you’d get more controversy, not less.
Right way IMHO, let a panel look at it after the event, discuss for as long as it takes and then hand out immediate bans retrospectively so cheats miss future games. May not affect the on field immediately but in time it will because players will then have the onus back on them to stay upright and not risk being called out for diving.