It would arguably be best for business if it releases in 2024. The Switch is in terminal decline, and I'd argue it's essential to keep their overall momentum going by releasing a new system. The only way the Switch 2 releases in 2025 is if the system and/or the games it needs are simply not ready to go next year. They are not going to delay it just to squeeze more out of the Switch. There is no good business reason for waiting any longer than necessary. The Switch is in decline. The longer Nintendo waits, the worse things will get.
On the hardware side of things, current projections have Switch hardware at 15M for the current fiscal year, a 16.5% decline from last fiscal year and a 48% decline from the Switch's peak year of FY2020-21. If Nintendo holds back on the Switch 2 until well into 2025 and the Switch drops to, say, 12M next fiscal year, that would make it the fifth-worst year for hardware shipments in the past 30 years. That's assuming they hit their target for this year. Things could end up being worse. What if they end up dropping to 10M next fiscal year in the absence of the Switch 2?
On the software side, things won't be as bad, but sales are still in decline. Software shipments for the current fiscal year are projected to be 180M units, a 16% drop from last fiscal year and a 23.4% decline from the FY2021-22 peak. If software sales in the 2024-25 fiscal year drop to, say, 140M units (a 22.2% drop), that wouldn't quite be close to the previous low of 75.34M units in the 2016-17 FY, but it would still be numerically closer to that low than to the Switch's peak, and would represent a drop of over 40%, or nearly 100M units, from the 2021-22 FY. And as with hardware, things could be worse. If they end up having to move the Switch 2 out to 2025, with nearly all their teams making games for the Switch 2, how many notable titles will the Switch be getting next year? Every game that's a likely contender for the Switch 2's opening window, like the next 3D Mario or Mario Kart 9, isn't going to be dropping next year. It's highly likely that Super Mario Wonder will be the last big title the Switch gets. It's definitely possible that the decline in software sales could accelerate.
The console market is cyclical, and as I said the Switch is in the "decline" part of the "grow-peak-decline" cycle. Console makers don't just wait until their old system is nearly dead to release the next one unless they have a good reason for doing so. Momentum is important. Getting a system out preferably no later than 3 or 4 years after a system clearly passes its peak is essential in keeping the inter-generation troughs from getting too low and keeping momentum solid. This is especially important now that Nintendo is a single-platform console maker. The Switch by itself cannot generate as much as what their handhelds and home consoles could do combined. Even with the N64 & GameCube running far behind the PS1 & PS2, Game Boy and GBA sales were enough to keep WW shipments above 20M every year from 1997 to 2005, with the Wii & DS kicking things into high gear. The 3DS—Wii U years were a very rough spot for Nintendo, hitting lows they hadn't seen since 1994 & 1995. The Switch did help right the ship, but by itself it only generated three years of 20M+ sales, and those years got a bit of an assist. With nothing else to fall back on, inter-generational transitions can get pretty rocky for Nintendo if they wait too long for a next-gen system.
You see the same thing with PlayStation and Xbox as well. Total worldwide calendar-year shipments of Sony hardware never dropped below 14M units in any year from 1997 to 2019, with an average of about 19.4M units per year during that 23-year span. That streak came to an end in 2020, but only because of... certain factors which resulted in both increased demand for and shortages of the PS4, which in turn resulted in rapid stock depletion, and the PS5's release in November wasn't enough to offset that. But the PS5's success has gotten them back to business as usual. You can see more or less the same thing with Xbox, even with the problems they've had post-360. While we don't have worldwide numbers, annual sales in the U.S. stayed above 4 million every year from 2006 to 2018, and, after a rough inter-generational transition that saw sales dip to just above 3M i bothn 2019 & 2020, got back above 4M in 2022.
Nintendo and their shareholders will not sustain continued, inevitable losses to revenues if they don't have to. Nintendo is a publicly-traded for-profit corporation. They're in this to maximize profits. And profits are down, and could face a surprisingly sharp drop if the the Switch 2 doesn't drop next year. Back when the Wii & DS were doing very good Nintendo was massively profitable, but by time they hit their transition to the next generation they were in a rough spot. They set a new record profit in FY2008-09, but just two years later, in FY2010-11 fiscal year, their net profit had declined by 66% from that peak. The 3DS had just debuted at the very end of that fiscal year, and the Wii U wasn't until the following year, so the woes those systems had weren't a factor, but declining Wii & DS sales were. That shows how quickly profits can drop in the face of declining sales.
I'm not saying the Switch 2 won't release in 2025, but Nintendo will not release it that year unless they simply cannot release it next year. A 2024 release simply makes more sense as it will reset the cycle and result in higher revenues next year, assuming it has a similar trajectory as the Switch and has some mega-blockbuster series that we haven't seen in a while released in the launch window.