I get the feeling Sony thought the transition from PS4-PS5 was going to land somewhere between PS2-PS3 and PS3-PS4. I don't think they expected to be able to crush PS4 yearly sales, which isn't surprising because without the pandemic their production so far probably wouldn't be that far off what would've been needed. I still think they would've been short and in demand regardless, but nowhere near the same level. PS5 could probably be at 25M sales right now if Sony had bet bigger than they did with PS4 right off the bat. I'd bet their big bet with PS3 and it's poor launch led to Sony being somewhat hesitant after learning all the hard lessons they did that gen.

I'm one of those PS4 players that isn't buying cross gen games because I rarely replay games. I'd much rather experience them on PS5.
I'm also one of those buyers who waits a few years until the units have any kinks worked out and once the price has dropped a bit. After the new heatsink revisions, I'd have bought a PS5 by now, full price, if I could walk in and grab it, but until I get lucky or can without having to hope there's one on the shelf, my game purchases are going to be at a minimum. In fact I'm seriously thinking of upgrading to Plus Extra just to get a big selection of games for cheap while I'm waiting for PS5 production to ramp up.

At least MS made the XB Series S. Can you imagine what things would be like right now if all there were was PS5(D) and XB Series X?

Delusional 

I think it's pretty much guaranteed that it's going to happen.  This generation is going to last longer for the Switch than normal because of chip shortages.  Also software sales continue to increase each year, and so do the number of titles released.  Nintendo is releasing so much software right now, that they aren't going to replace the Switch any time soon, and even when they do it will still sell decently for a few years even after the successor releases.  Also, Switch hasn't even had a price cut yet.  There are so many reasons why it's just going to keep selling.

I was expecting a Switch 2 release on March 2024, but now, I can see a new console most likely on March 2025. 

Nintendo is going to do a price cut when Switch production supasses demand, and even before that we can expect new bundles with free games.

Nintendo has all the damn cards: New Bundles, Price Cut, Unnanunced 2023/2024 Games from all the studios for one console ready for a future Nintendo Direct.

At this point, a Spring 2023 successor will not happen or it would have already been announced formally.

Nintendo DS announced November 2003 and releases November 2004

Nintendo Wii announced (as Revolution) in 2004, released 2006.

Nintendo 3DS announced March of 2010 and released February 2011

Nintendo Wii U announced in April 2011 (as Wii successor), shown during E3 2011, released in 2012

Nintendo Switch announced as NX in 2015, in April 2016 they stated they planned to launch the system March of 2017, October 2016 they unveiled the console. 

Basically, Nintendo would have given us at the minimum a codename or an official announcement other than "we are always working on new hardware"

I hope the Switch successor isn't until 2024 personally, but this is Nintendo and they're anything but predictable, so I don't feel secure in ruling out a 2023 replacement at this point.
Like most systems replaced in recent years, (3DS, PS4, Xbox One) I don't think many Switches will be made once the successor hits shelves.