Personally I think it could work, if done properly
Instead of HUD Radar, you have focus mode. Which fits with the games tone better than an onscreen radar does
And since Focused mode is based solely on sound, it would force methodical tactical play and increase the tension more than a constant radar
Haha radar! Only awful multiplayer games have those. We don't really need a 'replacement' for a radar because that kind of thing doesn't belong in this game anyway.
However, yes, maybe revealing sounds would encourage stealthy playstyles.
I understand what they're trying to do with this system though, which is to try to best incorperate a players footsteps with where they are in the map. We can do this in real life pretty easily, judging vibrations coming from various forms of movement and pin-pointing where exactly they came from. However putting your ear on a wall or on the ground and seeing a batman style view of where the enemy is, eh, I'm not sure how much I'd like that in MP. I'd rather hear footsteps, or a gun shot, and travel towards that direction, and hunt from there. Instead of immediately knowing where that guy is because I can see through walls. MP can encourage stealthy playstyles without this mechanic IMO.