There have been non-stop updates from 2011+ and I am pretty sure that the 2015+ owners have nothing to worry about.
The only confirmed updates, (as per leaked internal documents) are as follows:
May 2011 Change of connecting rod fastening method,
August 2011 Applying of connecting rod plating specification,
June 2012 Increase of bearing oil gap,
August 2012 Connecting rod material change,
Jan 2013 Crankshaft blast application,
September 2013 Crankshaft material change
If Hyundai engineers correctly identified and rectified the root cause of the engine failures, we shouldn't be seeing similar failures in 2015+ models.
I went back to carcomplaints.com, checked Korean forums and read carefully about the engine failure reports that occurred in 2015+ Hyundai/Kia vehicles equipped with 2.4L/2.0T engines.
In some cases, the failures happened within 500 miles after an oil change, or within 1 month after dealership oil change, etc. There was one case where the person said he checked the oil level right before driving, but it still failed. One person in Korea said the oil was changed every 3000km with synthetic oil, but still ended up with a loud engine knock.
You keep mentioning that the synthetic oil, short OCI, higher grade oil, better filter, frequent dipstick checks, and intake valve cleaning will be the cure of this problem, but I can't be as certain.
I don't think anyone, not even Hyundai's engineers, has been able to pinpoint the exact cause/causes of the problem. It is most likely due to multiple factors, and fixing one part of the equation (maintenance), may not be the solution.
At this point, whether the engine fails or not is more of a luck of the draw. The chance will increase with higher mileage.
I, too, would like to be able to say that "the 2015+ owners have nothing to worry about" for the sake of all the Hyundai/Kia owners. I would like to be able to say that Hyundai/Kia is a reliable brand and recommend their products to friends and family. Sadly, we know that is not the case after 2011.
This incident was reported on carcomplaints,
" I was in a 2015 Kia Sorento LX (enterprise insurance rental) traveling on crabb river road, (a city street) sugarland, Texas. I fully stopped at the traffic lights because it was red. Once lights turned green, I put the vehicle in motion by stepping on the gas pedal to accelerate but the car felt really sluggish so I gave it more gas in order to gain enough speed as I was about to go over some railroad tracks (approx. 55+ mph) which were on a road that was on an incline. Right as the car reached the tracks, the engine stalled, the steering wheel locked and I lost all control of the vehicle and it dove into a ditch; plowed directly into a steel billboard pole which was cemented into the ground because the brakes became unresponsive. There were no warning lights on the dash prior to the crash. Even though I was fully buckled, the seatbelt did not prevent my head from violently hitting the windshield and bouncing off the steering wheel since none of the 8 airbags deployed. I suffered near fatal injuries including a broken back (L2 fracture), spinal cord, head, eye, chin, jaws, neck and hip; broken teeth, permanent disfiguration (18 stitches), some vision & hearing loss from nerve damage and ptsd, mental anguish, chronic migraines, extreme stress, terrible recurring nightmares, etc. I'm a 5'2" woman and my chest was pinned to the steering wheel upon the impact with the pole and the fire dept. Had to free me and lift me up to the emts. I was transported to the er of a hospital by ambulance and later transferred to the trauma unit of memorial hermann hospital due to the severity of my injuries."
This forum will have inherent bias as most of the posters are owners of Hyundai vehicles. It would be beneficial to try to keep that bias in check and try to get the pertinent facts.