I don't think Gilchrist did do that, though - I don't think anyone can or ever will. As I say, having a genuine Test-class batsman who can nonetheless keep wicket at least as well as anybody else is not something anyone is going to be able to get very often. A Stewart, Flower or Gilchrist (and sometimes Sangakkara) is a rare thing. Nor is it exclusively a modern thing; Leslie Ames in the 1930s has been mentioned by bagapath; 50 years before him there was Billy Murdoch. Clyde Walcott did the job in the 1950s. Jeffrey Dujon did for a time in the 1980s, before his batting declined. Denis Lindsay in the 1960s.
Even now, we have mere Bouchers, Jayawardenes, McCullums, Kamran Akmals, Ramdins; all capable lower-order batsmen, but never people who would make the side purely for their batting.
And like the batsmen-wicketkeepers, wicketkeeper-batsmen have always been present even before the 1980s and 1990s: Engineer, Marsh, Knott, Murray, etc.
The batsman-wicketkeeper is neither something that started with Gilchrist nor something that will ever become a trend. It is something that will be a rare bonus, because only a phenominally gifted cricketer will ever be able to do it.
RIP Fardin Qayyumi (AKA "cricket player"; "Bob"), 1/11/1990-15/4/2006