I don't think "$399.99 is pushing it" at all.
As I've shown Nintendo's audience isn't children begging their cash strapped parents to buy the system. Most of the audience base is adults with their own income, $399.99 is not a lot of money for an adult. Aside from that $399.99 for fall 2024 would be well in line with other Nintendo consoles (not sure why you guys are comparing only with portables, I don't remember the GBA being able to dock to the TV and being able to run console games in high definition like Zelda: Wind Waker).
The Super NES' launch price today would be $441 US. The N64's launch price with inflation today would be about $383. The GameCube would be $342 and even there Nintendo sold that system at a loss initially because they were hellbent on the idea that having a cheap price would be a big factor against the PS2 (skip to the end: it wasn't).
$399.99 is "pushing it" only if their 1st year lineup is weak, which they'd be morons to repeat again. They should have Mario Kart and the next 3D Mario locked up for the first 8 months at least.
That or there is something unappealing about the hardware, but I struggle to really figure out how they could screw up a Switch successor, this is not the Wii or DS successor where the successor had to play to the blue ocean crowd at a time when motion control (copied by both Sony and MS in 2010) and touch control (becoming widely available in smartphone gaming with the App Store's gaming lineup starting to explode in 2010/2011) were not unique any longer (thus becoming a red ocean).
If the Switch OLED has been selling well for almost 2 years now at $350, saying "$399.99 is pushing it!" for a system that's going to be a full generation upgrade and possibly will offer an even bigger screen and potentially more on-board storage ... to me doesn't pass the smell test.
If they've screwed up the launch lineup, marketing or design then a cheap price isn't going to help them as much as people think.
The library for the first 8-12 months (not just the first month) is more important than $399 or $449. Stacking the 1st year lineup is the most important thing for Nintendo, IMO their products are more sensitive to software availability, the price is not a primary factor for their hardware any longer. If they have a weak first 8-12 months software wise then $299.99 isn't going to do shit. They have to be ready to go with Switch 2, all guns blazing software wise, that is the key to everything, and not just 1 or 2 games but a fairly rock solid roadmap of what is your third big game? Fourth? Fifth? The 1st year should basically be mapped out already today.