So this was discussed on today's Spawn Wave, and John seems to think, based on a more accurate translation, that the "early 2024" time frame is speculation on behalf of the author of the original article and not coming from the manufacturer:
He still thinks the Switch successor will be released holiday 2024, and that's where I'm at too. Parts manufacturers would naturally see an increase in profits prior to the release of the actual console, since they're at an earlier point in the supply chain.
I won't be surprised if it's not hardware BC with Switch. They know people will buy it anyways.
I don't know why people are constantly saying variations on this "people will buy it anyways" line about the Switch successor, when there's absolutely no evidence to back up such claims. Nintendo has way higher than normal volatility when it comes to console sales. In just the last four generations they went from the Gamecube selling <22 million to the Wii selling >101 million to the Wii U selling <14 million to the Switch selling 125 million and counting. This is not indicative of a locked-in, highly loyal customer base.
As far as backwards compatibility is concerned, I could see it going either way. Nintendo has a mixed record on this front. They've had multiple systems that launched with backwards compatibility (GBA, DS, 3DS, Wii, Wii U), but it's far from all of them. I don't think the lack of backwards compatibility on the Switch tells us much either way, since it would have been physically impossible to include 3DS BC because the Switch is a single-screen system and obviously there was no way they could have included a drive for Wii/Wii U discs on a handheld.
If I had to guess, I'd say that the Switch successor will have BC initially, but that it will be omitted from the inevitable Switch 2 Lite to cut costs. This is basically how Nintendo has handled it in previous generations.