The last calendar year in which more revolvers than pistols were manufactured in the US was 1986. Since that time, more pistols have been annually manufactured than revolvers.
Some interesting numbers from the BATFE in its 2017 report.
https://www.atf.gov/resource-center...tates-annual-statistical-update-2017/download
Nowadays it's not nearly as labor intensive to produce revolvers, either. From my notes in a revolver armorer class more than 10 years ago ...
It previously took 7 machines (and machine operators) to make a revolver hammer. Now they come out of a MIM mold and are much more precise.
Making the Old Model revolver frames required 75 machining steps (without the barrel), but the New Model revolver frames only require 3 machining steps, and then they're off to heat treat.
Handgun (and other) production occurs in "cells", with small groups of assemblers (and fitters, for some revolvers), and production is much more efficient and streamlined than in earlier years.
Another guy at the factory once told me that there was a significant improvement in revolver production when the factory decided it was time to tighten the normal manufacturing tolerances of critical revolver parts to a much tighter tolerance range (based upon analyzing Performance Center specs and production), than used to be possible in the older hand-fitted revolver production. He used to be in revolver production in the 70's, and then doing custom work (before moving over to the then-new Auto Improvement Program - AIP - during the end of the 2nd gen pistol production). He said the older revolvers pretty much had to be hand-fitted to get them to work with the older production parts and tolerances.
Now, personally, IF (hypothetically speaking) the company were to reinvigorate the 3rd gen pistols and begin even limited production again, I'd not be surprised to find that their ever improving cutting edge manufacturing methods would probably allow them to simplify some of the steps. While the sear release lever would probably still require some hand-fitting/gauging, the tolerances for slides and extractors might (
might) reach the point where they no longer required hand-fitting.
I say that because in my last 3rd gen recert I came across a late production 5906TSW training gun in which an extractor dropped in the slide and was within good spec, without any filing/fitting. The instructor said that he'd seen that happen only a couple times, but that they were in another recent class. He speculated that the improvements in manufacturing tolerances were reaching the point where specs were becoming more precise.
It was shortly afterward when we were told in one of our M&P pistols recerts that armorers were no longer being required to buy an extractor bar gauge for the .40/357 guns, because the factory had determined the newest guns were precisely enough made that the extractors were dropping in.
As a matter of fact, when I'd previously repeatedly called and asked if they'd made an extractor block gauge for the 9/.45 M&P's (because I like to have armorer tools

), they kept telling me they didn't consider it necessary for those calibers.

They said the extractors and slides were being made to such close tolerances that the extractors were dropping it (like everyone else's plastic guns).
So, maybe if they ever did decide to make some 3rd gen's, we'd see them undergo yet another revision and improvement in manufacturing.
Don't hold your breath, though. (But, as is easily said with S&W, in general ... never say never, because they change their minds all the time.)