The DSi being announced on 10-2-08 seems likely, as that info was added on that day. But I don't see anything that looks like a source. As for the discontinue date for DS. Warning. It is quite long:
On March 1, 2011, SWFlash added a 2009 discontinue date saying in the summary, "It was discounted since DSi was released" SWFlash hasn't been on since 2014. This was the first time it was mentioned with the exception of Wario No Need a discontinuation date of 2010 or 2011 in 2010, but there was no proof and was removed. On April 24, 2011, Mario54671 changed dis to 2011 with this in the summary: "The DS Lite wasn't technically wasn't discontinued until recently.
http://www.holyfragger.com/handhelds/nintendo_ds/news/?a=2089" Which is DS Lite only. Although, it does mention that the original was on the market for less than 3 years, suggesting a 2007 date. Plankton5165 added (NDS only) on April 28, 2011. Then "Dis=Nintendo DS: 2011<br>Nintendo DS Lite: Not Yet" the next day. Mariowikijp changed dis to phat 2009 and Lite 2011. June 30, 2013 had an IP vandal messing with the dis dates for DSi and DSi XL, but were removed. Another on July 7, 2013 who removed all of the release and replaced with 1-1-1981 and had dis 1-1-2009. Sugarlover was another vandal that was like the first, but on Sep 29, 13. It was removed because it wasn't 2016 yet. Another IP put 2013 on May 19, 14. Another IP removed dis all together on Nov 7, 15. General Xerneas added it back in on May 16, 2016. Another IP made it 15 on August 19, 16, but was reverted the next day. Then Marole3 on that day made it 2014, according to Wikipedia, but was also reverted. ON Sep 19, 16, another IP made it 2014. On June 27, 2017, Tryloubliss changed it to this: "'''Nintendo DS:''' 2009<br>'''Nintendo DS Lite:''' 2011<br>'''Nintendo DSi/Nintendo DSi XL:''' 2014". On Dec 23, 2019, CaillouFan changed the first to 2013, citing the same source as Wikipedia. It was reverted the next day, where the ref neededs were added to all by Mario jc. On March 16, 20, Octoling Rendevous removed DSi from the info box. On August 31, 20, another IP changed first to 2011, but was reverted. This was all before Ray Trace added a date to Lite.