The real adpocalypse won't be the likes of us blocking ads, nor all those millions out there. They'd lose some clicks or views or whatever they're charging for. The entertaining budget might be cut. Some smaller firms might go under or get merged. Some of the cannon fodder might have to go back to selling double glazing, pimping contractors or whatever they were doing before but on the whole the industry would survive to carry on its noxious ways.
What the ad industry should be really worried about is some of their clients who will undoubtedly be adblocking as well. After all ads get in their faces as much as ours. Eventually some of them will start to realise that they're not special snowflakes and that the way they see other advertisers is the way they're seen by the rest of us. Then they'll wonder why they're paying good money to be perceived as pestering brats who everyone tries their best to avoid. The industry won't worry about ads not being seen as it will about ads not being sold.
I suspect that the initiative comes from those in the industry who've sussed this out. But they have some problems.
First they have the problem that not all the industry are going to share this insight. We've had a flavour of the others from their regular cheerleaders who pop up here. They have an impenetrable sense of entitlement. They behave like badly brought up children who believe almost everybody loves them except for a few who are simply misinformed. It may well be that trying to accommodate this faction is why their idea of LEAN is nothing like what would be acceptable.
The next problem is that once they have their idea of LEAN they have to get it accepted by their industry. Given the general sense of entitlement there'll be a good number (?most) who think it's a good idea in general and if everyone else goes along with it we'll be able to get away with ignoring it. Good luck with the cat herding.
Then, however, much industry buy-in and even compliance they get they still have the problem of malvertising. These people aren't even in the industry, they're just riding on top of it. They're not going to be brought into the fold.
So not only are they going to have to bring the actual advert creators, or a good chunk of them, into line, they're going to have to set up much better engineered networks to ensure that only compliant ads get on there and that malvertising absolutely can't; the latter ought to be backed up with a scheme to accept unlimited liability for damage. Given the complexity of their present setup such re-engineering is going to take some doing. I doubt they could succeed without shutting down a lot of the players which seems unlikely to happen.
If the best that they can achieve would be some "good" networks they then have to persuade publishers to only deal with the good ones. Nobody will trust a publisher who unpredictably slings a mixture of LEAN, non-LEAN and malicious ads.
Finally they need to find a way in which they can tell the public which publishers guarantee only to use the "good" networks so they could be whitelisted. Nobody's going to turn adblockers off if one site is safe and the next isn't, especially if the bad one is linked from the good.
Those are the technical challenges they face and have to solve before they can even start asking us to trust them at which point they have further challenges because the ad industry is its own worst enemy despite all our shouts of "Not while I'm alive, it isn't.". By the very nature of their business we regard them as liars. They've also pissed us off to the extent that they have zero goodwill to trade on. And finally I think they still have an attitude problem which isn't going to go away and isn't going to help any charm offensive they might try to mount.