@Leahcar: To be honest, I REALLY REALLY hope they don't end up rushing the Switch version. Now that I think about it, X and Y developed a somewhat rushed feel by virtue of being the first mainline 3DS title. Try as Game Freak might, they didn't quite optimize everything to accommodate the system.
Henceforth, I'm expecting Gen 8, if it even comes to that, to ship out by 2019 at the earliest. Even Gen 6 took time to start up, believe me!
This list uses the earliest release dates, usually for Japanese versions.
Gold and Silver: November 21, 1999 (Released 3 years and almost 9 months after Gen I; released a year and over 2 months after Yellow)
Ruby and Sapphire: November 21, 2002 (Released exactly 3 years after Gen II; released a year and over 11 months after Crystal)
Diamond and Pearl: September 28, 2006 (Released 3 years and over 9 months after Gen III; released 2 years and 12 days after Emerald)
Black and White: September 18, 2010 (Released 3 years and over 11 months after Gen IV; released a year and 6 days after Johto remakes)
X and Y: October 12, 2013 (Released 3 years and almost a month after Gen V; released over 8 months after Black/White 2)
Sun and Moon: November 18, 2016 (Released 3 years and over a month after Gen VI; released a year and over 11 months after Hoenn remakes)
See where I'm going?