The 20/40 is a great rule just as the 40/20 is. The fact coaches are too set in their risk averse ways to take advantage of it is not the rules fault.
Bring in other rules to make teams have to take more risks.
I love the 40/20.
I just don't think the 20/40 is necessary? It's fiddling for fiddlings sake. What glaring issue in the game is it solving? That's the reason for rule changes. I quite like it that if you defend well, with discipline & aggression you might just be able to, you know, get some reward for that like having territorial dominance for a few sets.
Then the other team has to work really hard or take a risk with some wide passes or produce a really great kick & chase to get out of it. You know, like a good game of footy. It might take them a few sets to work back into it or they might produce a break or concede a try, but pressure can be applied & then withstood or crack you open. A contest.
Adding more escape card lottery rules doesn't do much for me I'm afraid. Dropped balls, strips, penalties, intercepts, line breaks, there's all kinds of ways to bust out of the 20m zone already. Why make it easier to get out of trouble, harder for good defence to be rewarded & reward kicking the ball out, which is why people find union so boring & incentivises kicking out which makes it less likely the games most exciting running players- the back 3, will get involved?
I like the 7 tackle set rule exactly because it encourages not kicking the ball out & keeping a game flowing & allowing running players to run.