Not replace the engines but redesign the oiling system so either the lifters get oiled first or install oil squirters in each lifter bore providing more oil to the lifters for the engines that have had verified failures. Then apply this redesign to the most recent engines coming out of the factory. I could almost guarantee one of these would solve the issue. Most recalls/extensions of warranties are for a very small number of vehicles, excluding Takata air bags, and most of those recalls are BULL**** anyway!!!
Again, look at the the 3.6L Pentastar . The engine had a very small percentage of drivers side cyl head failures. So what did Chrysler do? The extended the warranty and redesigned the head to prevent the issue from coming back. They didn't replace every cyl head in every 3.6L. Only the ones that had the failure.
As far as emissions goes, WHO CARES ABOUT EMISSIONS?!?! I could care less about that crap! I'm more worried about all the people I see on a daily basis, who I'm being endangered by, with metal to metal brakes, steering and suspensions that are shot to ****, puking oil, ps fluid, brake fluid and coolant all over the place and when brought to the customers attention they tell me, "I have a mechanic that takes care of my vehicle and is cheaper than you guys!" Both of which are BS most 9 times out of 10!!!
Lastly, another one to look at, as far as a BS extension of warranty, is the Grand Cherokees that have the leather dashboard that's pealing back. They extended the warranty on THAT for 10 years! That's a $2500.00 job at warranty rates. Speaking of which, I had a customer 2 weeks ago who came in because their idiot "private mechanic" saved them so much money by going to him and didn't solve a damn thing yet charged them $1400.00 for a bunch of crap that didn't need to be done and wasted a week of their time. Then my tech gets it and has it squared away in on one day for about $400.00. The sad thing is his dash was pealing back and I was hoping to get it covered for them but because they wasted a week at their "private mechanic" the extension of warranty had expired 3 days prior to bringing it to me. Yea that sounds like it was a real bargain, huh???