Let me repost this yet again:
Decided to do a bit of research (read: skimmed Wikipedia) on this and other Nintendo systems to give a bit of perspective on this and the potential timetable for the succ's launch after it finally gets announced.
Note that I'm considering the "reveal" for each system to be the first time system+controller+software were shown publicly, since the reveals of some of these systems were super piecemeal and staggered.
Nintendo Switch
NX announcement: March 2015
UPDATE: Here's Iwata's quote on the NX, translated officially by Nintendo: Also, Iwata said Nintendo's new membership s…
www.eurogamer.net
Switch reveal: October 2016 (1 year, 7 months after announcement.)
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www.youtube.com
Worldwide launch: March 2017 (2 years after announcement. 5 months after reveal.)
Consoles
Super Nintendo
Annoucement: September 1987
Reveal: November 1988 (1 year, 2 months after announcement.)
JP launch: November 1990 (3 years, 2 months after announcement. 2 years after reveal.)
Nintendo 64
Project Reality announcement: August 1993
N64 reveal: November 1995 (2 years, 3 months after announcement.)
Popular Mechanics inspires, instructs and influences readers to help them master the modern world. Whether it’s practical DIY home-improvement tips, gadgets and digital technology, information on the newest cars or the latest breakthroughs in science -- PM is the ultimate guide to our high-tech...
books.google.com
JP launch: June 1996 (2 years, 10 months afer announcement. 6 months afer reveal.)
Gamecube
Dolphin announcement: May 1999
After a brief introduction by Nintendo's Executive Vice President of…
web.archive.org
Gamecube reveal: August 2000 (1 year, 3 months after announcement.)
TOKYO - Nintendo has officially announced the name of its next-generation console. First details inside.
www.gamespot.com
JP launch: September 2001 (2 years, 4 months after announcement. 1 year, 1 month after reveal.)
Wii
Revolution announcement: May 2004
We take a look at the man behind the company in this in-depth feature about Nintendo's president.
www.ign.com
Controller reveal: September 2005 (1 year, 4 months after announcement.)
news
www.gamasutra.com
NA launch: November 2006 (2 years, 6 months after announcement. 1 year, 2 months after reveal)
Wii U
Wii successor announcement: April 2011
Today in Japan, Nintendo confirmed the upcoming release of the Wii's successor. The still-unnamed console will be revealed at this year's E3 gaming expo in Los Angeles in June.
kotaku.com
Wii U reveal: June 2011 (2 months after announcement)
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www.youtube.com
NA launch: November 2012 (1 year, 7 months after announcement. 1 year, 5 months after reveal)
Handhelds
Game Boy Color
Announcement: March 1998
JP launch: October 1998 (7 months after announcement)
Game Boy Advance
Announcement: September 1999
Gaming news from Pocket.IGN.com
web.archive.org
Reveal: August 2000 (11 months after announcement)
At long last, the public has been shown Nintendo's next-generation handheld.
web.archive.org
JP launch: March 2001 (1 year, 6 months after announcement. 7 months after reveal).
Nintendo DS
Announcement: November 2003
Early Thursday morning Nintendo confirmed that it had posted a loss for the beginning half of the fiscal year, the first time ever in the company's history. It also said it would develop a new game product which would not be the successor to GameCube or Game Boy Advance for release in 2004, but...
ds.ign.com
Reveal: May 2004 (6 months after announcement)
NA launch: November 2004 (1 year after announcement. 6 months after reveal.)
Nintendo DSi
Announcement/reveal: October 2008
JP release: November 2008 (1 month after announcement)
Nintendo 3DS
Announcement: March 2010
Reveal: June 2010 (3 months after announcement)
JP launch: Feburary 2011 (11 months after announcement. 8 months after reveal.)
New 3DS
Announcement/reveal: August 2014
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www.youtube.com
JP release: October 2014 (2 months after announcement)
If we treat the announcement that the Switch 2 is being worked on back in May as the "Announcement", then a November 2025 release would still make it the fastest turnaround on a home system Nintendo's ever had.