I assume what they are aiming for is more entertainment, i.e. not disallowing goals because someone is marginally offside. I understand they did a survey of players and the attackers were in favour and defenders were not (surprise surprise).
Klaus wrote:
The biggest issue with Wenger's idea for me is that as long as you leave half a toe (or a bit of your upper arm, the way handball is defined these days) onside you can be well ahead of the defender, and that's not how offside was intended to work either. I imagine it could mess up setpieces in particular. And while I agree that more goals is a good thing there are better ways to encourage them than to mess with the offside rule too much.
There would defo be a lot of commotion initially, I don't think I have the will to put up with 12 months of pundits and maybe coaches claiming 'they don't understand the new offside' even though my kids would probably get it, and they'd inevitably claim it makes defending impossible etc. I think defenders would adapt, attackers would adapt, and it would eventually feel very normal.
I don't think much would change in terms of defending, attackers can't 'make sure' they have something onside without it impacting their momentum. Even on set pieces it won't make a huge difference, they'll touch tight regardless of who's marginally ahead, and by the time the ball floats in there will be plenty of time to adjust. I don't think it would result in deeper defences, because that opens up an entirely new set of problems for a team and a defence. But you'd only find out after a trial I guess.