My take is pitches flattening out around 2000s had an impact over Wicket keeping dynamic, when the pitches are easy paced and the bounce is true it becomes a lot easier to keep and bat, but when the bounce is inconsisent and the pace is uneven it becomes harder to keep.
The 1930s was flat, but they had a bunch of sticky wickets and they were difficult to keep on and thus specialist keepers were required, same way in the 1960s the keepers were still picked on skill but by the end of the decade, Farokh Engineer and Alan Knott were actively picked for batting, the trend kept in the 1970s and the 1980s as well, Dujon and Healy made teams and while they were better batsmen then the likes of Evans and Taylor, their batting didn't exactly make much of a difference usually, Dujon was in the team after 1985 when he was a tail ender for multiple years, by 1990s stickies were long gone and when the wickets started getting flat by the turn of the millenium, it became a norm to have keeper bats.
If you see in recent years, with more competitive pitches, keepers are again struggling, Pant barely managed to keep on a flat pitch, Smith is not great either and dropped the series in Pakistan when he dropped Salman Ali Agha, Carey dropped some absolute sitters on that fast uneven bounce Bridgetown wicket from the last test and so forth. At one point, if the pitches remain this way, the world isn't exactly drowning in batting talent to the point that someone cannot replace the likes of Pant and Jamie as keepers, Jamie would likely be replaced once he moves up the order and Stokes is gone, would play as a Batsman with a better keeper at 7 and Pant would likely drop the gloves to Jurel at some point if he bends his knee.
All in all, I'm in more agreement with Thala here, I think keeping is getting harder to do and if that happens then I think specialist keepers would and should return.