I think the best example of how predictable the core audience is would be looking at the top 10 best selling games list NPD puts out every December and noticing it's almost identical to the previous year (sans the subtitle or iteration number in the game titles). Even for the games that aren't the same they're usually similar in concept like trading GTA for Red Dead or Halo for Battlefield.
I mean seriously:
2013:
2012:
2011:
Annual 2011 Top 10 Games (New Physical Retail only; across all platforms incl. PC) Rank Publisher
1.) Call of Duty: Modern Warfare 3 (360, PS3, Wii, PC)** 1 Activision Blizzard
2.) Just Dance 3 (Wii, 360, PS3) 2 Ubisoft
3.) Elder Scrolls V: Skyrim (360, PS3, PC)** 3 Bethesda Softworks
4.) Battlefield 3 (360, PS3, PC)** 4 Electronic Arts
5.) Madden NFL 12 (360, PS3, Wii, PSP, PS2)** 5 Electronic Arts
6.) Call of Duty: Black Ops (360, PS3, Wii, NDS, PC)** 6 Activision Blizzard
7.) Batman: Arkham City (360, PS3, PC)** 7 Warner Bros. Interactive
8.) Gears of War 3 (360)** 8 Microsoft
9.) Just Dance 2 (Wii) 9 Ubisoft
10.) Assassin's Creed: Revelations (360, PS3, PC) 10 Ubisoft
2010:
Annual 2010 Top 10 Games (New Physical Retail only; across all platforms incl. PC) Rank Publisher
01. Call of Duty: Black Ops** (360, PS3, Wii, PC, NDS) ACTIVISION BLIZZARD
02. Madden NFL 11 (360, PS3, Wii, PS2, PSP) ELECTRONIC ARTS
03. Halo: Reach** (360) MICROSOFT
04. New Super Mario Bros. Wii (Wii) NINTENDO
05. Red Dead Redemption (360, PS3) TAKE 2 INTERACTIVE
06. Wii Fit Plus** (Wii) NINTENDO
07. Just Dance 2 (Wii) UBISOFT
08. Call Of Duty: Modern Warfare 2** (360, PS3, PC) ACTIVISION BLIZZARD
09. Assassin's Creed: Brotherhood** (360, PS3) UBISOFT
10. NBA 2K11 (360, PS3, PS2, PSP, Wii, PC) TAKE 2 INTERACTIVE