Well, look what happened with the 780s.
People started noticing it's performance dropping way below AMD equivalent cards soon after the 9 series was released. Even in some older games it started performing worse.
That scaremongering!
Few months ago Techspot published very interesting Then and Now article compared 6 generation of Geforce GPUs ran with all graphics settings maxed out.
http://www.techspot.com/article/1191-nvidia-geforce-six-generations-tested/
6 generations Geforce cards tested:
GTX 1080 - 27 May 2016
GTX 980 Ti - 2 June 2015
GTX 980 - 19 Sept 2014
GTX 780 Ti - 7 Nov 2013
GTX 780 - 23 May 2013
GTX 680 - 22 March 2012
GTX 580 - 9 Nov 2010
GTX 480 - 26 March 2010
Games benchmarked:
Rise Of Tomb Raider - 28 Jan 2016
The Witcher 3 - 18 May 2015
Dragon Age: Inquistion - 21 Nov 2014
Sleeping Dogs - 8 Oct 2014
Metro 2033 Redux - 27 Aug 2014
Watch Dogs - 27 May 2014
Thief - 28 Feb 2014
Battlefield 4 - 29 October 2013
BioShock Infinite - 25 March 2013
Tomb Raider - 5 March 2013
Crysis 3 - 19 Feb 2013
It is really amazing that GTX 480 can run Rise Of Tomb Raider fine when the driver stopped optimised 5 years ago.
Battlefield 1 open beta at 1080p on DirectX 12 ran just fine on GTX 680 and 780 with no drivers optimised.
Edit:
Oh I just googled tried to see if Techspot had Then and Now article on Radeon generation and found 5 generations article below.
http://www.techspot.com/article/942-five-generations-amd-radeon-graphics-compared/page4.html
Surprised GTX 980 performed very well compared to 290X 2 years on when Nvidia stopped optimised drivers, it is incredible GTX 480 outperformed 5870 in all games.