Spring 2023 is my vote. I think this date is most likely based on Nintendo’s comments.
• Consoles are planned years in advance, as Furukawa has stated, not developed and saved for when it seems like a good time to launch. It makes little sense for developers to create software intended to launch the console only to sit on it, as that creates huge gaps in their schedules.
• Furukawa announced in January 2020 was the midway point of the Switch’s lifecycle which indicates they were looking at a late 2022 release date back then. Although, he said similar comments through 2020 and 2021. This doesn’t necessarily mean anything for Switch 2 since consoles can exist at the same time - for example: PS2 had a 10 year lifecycle, the last 3-4 years were alongside PS3.
• Furukawa also said they were breaking tradition. This could mean multiple things, but I think he means Switch 1 and 2 will run in parallel for some time rather than Nintendo’s traditional slash and burn the previous generation to make way for the new one. Why? Nintendo ran a little experiment with 3DS, seeing what would happen if they supported the 3DS during the Switch; sales went up year over year.
• Furukawa said that Switch 2 would expand the ecosystem they built with the Switch. This indicates that rather than starting from scratch on the next platform, there will be continuity. This is how it works on most other platforms: iOS, MacOS, Windows, etc… Another supporting point is Nintendo is not likely using a drastically different hardware or interface for the next generation Switch given their deal with Nvidia.
• The odd Breath of the Wild 2 delay to “Spring 2023” is a smoking gun. Zelda, particularly Breath of the Wild, is Nintendo’s flagship franchise. It is the ideal game to launch Switch 2 with. The game has been in development a very long time and is unlikely to have had the same developmental hurdles of Breath of the Wild 1 based on what we know. Even with Corona, it shouldn’t have this extensive a decade cycle. What is the reason? Simply polishing it up isn’t a great reason to miss the holiday season since polish can be applied after launch with updates (like with the first game). A Switch 2 release time would be a reason.
• When asked if Switch 2 was launching this 2023 fiscal year, rather than the usual unambiguous “no” Furukawa dropped the classic “No comment” line. For those unfamiliar with the tech industry from at least the 1980s to early 2000s “no comment” translates to “Probably, but we’re not ready to make an announcement on this yet.”
So, based on their comments, I think a Spring 2023 release seems most likely, Summer 2023 (maybe late winter in case Nintendo decides a little earlier in March or something) second most likely, and so on. And there are some other things that can be gleaned from the info. Switch 1 won’t be killed off before as has been Nintendo’s general (bad) strategy before this time. Switch 1 will expand the lower tier while Switch 2 will take the upper tier and play all Switch 1 games - perhaps with higher settings for those devs who wish to update: many games on Switch already have those capabilities given they were ported from other platforms with multiple tiers (both hardware and OS).
It's actually the opposite: Spring 2023 can be ruled out based on Nintendo's comments. Replying to your individual points:
1. It does make sense to sit on finished games for strategical reasons concerning console momentum. How else do you think that Xenoblade Chronicles 3's release date could be moved forward by about two months? Originally, Splatoon 3 was intended to go into the July slot, but that game needed more time to complete its development while XC3 did not, so their release dates got swapped. Another example is Switch's launch itself which was delayed by about four months in order to stack the first party release schedule properly.
2. What Furukawa said was that Switch had just entered the middle of its lifecycle. The way this is framed differentiates it clearly from the midway point of a lifecycle. It only makes sense that Furukawa kept saying the middle of the lifecycle in following years, because the middle of the lifecycle is a phase (a.k.a. a timeframe) that lasts years, unlike the midway point which would refer to a specific single point in time.
3. Furukawa said that Nintendo has the intention to give Switch a longer lifecycle than their previous consoles. This refers to their successful consoles that got six years before replacement, so spring 2023 - which is six years - could be safely ruled out for a long time by now.
4. None of this refers to the launch timing of a successor.
5. Another good reason for a delay would be what I mentioned in point 1. Switch's momentum is too strong to need three guaranteed 10m+ sellers in the second half of 2022 to keep the train going, plus there's a cap to how many consoles Nintendo will be able to sell this year as the component shortages persist. However, I don't put it past the Zelda team to really need all those additional months to finish the game, because this particular team is notorious for its delays since more than two decades by now.
6. Read Q/A4 here: https://www.nintendo.co.jp/ir/pdf/2022/220511_2e.pdf
You'll notice that Furukawa wasn't asked whether Switch's successor would launch during this fiscal year, so your seemingly strongest point has no basis in reality.