The people saying over $400 is not much more expensive are ignoring Nintendo's entire history and philosophy of being the affordable system. Over $400+ means Nintendo is abandoning the pricing strategy they've always stuck to. It's not going to happen. Honestly $399 is probably not going to happen except for an upgraded version later on (similar to the OLED this gen). And we all know how Nintendo doesn't like price cuts, so they aren't going to make another 3DS mistake and release a $450 or so Switch 2 and then have to cut the price by like $100 within the first year and take losses and get bad press and slow sales. That's an awful combo to shoot themselves in the foot with.
If they have a single SKU at launch it'll almost certainly be $350 or very close to that price. If they do two SKUs, which I could totally see happening, they could do an LCD + less disk space model for like $330 and an OLED + more disk space model for $380 or at absolute most $399. Though if they do launch with something near $399 I would expect a $50 price cut after a couple years so they could launch a premium model at $399 later on. I don't see any model of next gen at any time coming with a price tag that starts with a "4".
I feel like people are throwing out these high price tags just because Switch hybrids are selling at $300 and $350. But you gotta remember Nintendo is making straight BANK on those systems. They could easily cut the price of those and still bring in good profit, they simply don't need to because Switch still sells very well. A generational leap over Switch doesn't mean the system is gonna cost $350-$400 to make. Depending on how high end they go, and depending on if they do one model or go with a base model plus a nicer model, next system is probably gonna cost somewhere from $300 to <$350 to produce, and the $350ish will probably only be for the nicer model if they go with a two SKU plan. A single model they are probably targeting around a low-$300 production cost and a ~$350 price.
Nintendo isn't dumb enough to ignore their market and put out a system that costs in the console range (ie $400+) and they know what happened last time they launched a system with a much too high price (the 3DS). They know their market is affordable systems and amazing games, not expensive systems with the latest high end tech.