Yeah, they discontinued support of the 3rd gen guns to peddal more of the plastic junk with lousy triggers they currently make.
But not to worry. In 28 years of shooting 39 different examples of 3rd gen guns, I only ever broke one part. A MIM mag catch on a 4516 LE special order gun. I replaced it with a forged part and never had another problem. Midway and Numrichs as well as Jack First have 3rd gen parts. I just got an order of recoil springs and mags from them last week.
And Apex Tactical, the company that gives the m&p everything that the factory cant be bothered to, like a decent trigger and accurate barrels, is going to start producing 3rd gen parts to take up the slack. Should parts even be needed.
So buy a 457 with confidence. I fire upwards of 800 rounds a month through mine. No problems or broken parts. Regards 18DAI