Very recently we have had:
Nadal reaching 8 out of 9 GS finals (from 2010 RG to 2012 RG, only failed in 2011 AO because of injury).
Djokovic reaching 8 out of 10 GS finals (from 2010 UO to current AO, only failed in 2011 RG and 2012 WB losing both times to Fed in the SF)
Of course Federer reaching 10 out of 10 GS finals at one point (and 8 out of 8 at another point, which gives 18 out of 19 GS finals).
Now Murray is playing his third consecutive GS final...
If Federer declines a bit more (because of age) and Nadal does not come back strong....we could have Djokovic-Murray GS finals many many times in the near future.
And some people still don't want to know that all this is totally related to homogenization of conditions in tennis...
I am not saying it is better or worse to have it like this (it depends on what every viewer prefers, I prefer variety and more than the same three players to be able to play GS finals, but other people may like to see the same players, all with basically the same style, in all GS finals all the time).