The last time doubles was a big deal at the slams was the the 1980s. You can see packed stands for the USO men's doubles finals with Mac, Edberg, Noah, Leconte etc playing specialists like Flach Seguso etc. Then in the 90s you see virtually no one watching finals with Woodies or Eltingh/Haaruis(and none of those guys were bad at singles, they were all in draws of singles as well). And then you got Nestor/Knowles/Paes etc and it got even worse. I remember Cliff Drysdale saying around 2000 in an interview online that anytime they showed doubles on ESPN, virtually every TV tuned in would switch the channel.
The ATP tried to basically eliminate doubles specialists around 2005(only allowing singles players into doubles draw), but the Bryan brothers sued and they backed down. They did go along with changing the scoring system to no ad and super TB in place of 3rd set in 2006. Originally ATP wanted to have only 5 game sets, but they caved on that after the lawsuit.
So really, doubles specialists have been a bit lucky the last 20 years to get a stay of execution in essence, not really surprised there eventually would be more changes(if this USO experiment with mixed doubles works, you can bet other slams will follow(I think attendance for doubles at RG is probably the worst of all the slams, they will be next I'm sure).