According to VGC, development kits for the next Nintendo consoles are with key studios and are planned to launch in the second half of 2024.
The article states that their sources have indicated that we can expect the next-generation Nintendo console to be similar to the Nintendo Switch in that it can be used in portable mode, with several of those sources suggesting that the console may launch as an LCD in order to make the console itself as cheap as possible.
VGC's sources were not able to confirm or deny whether the next-generation Nintendo console will have backward compatible support, although with the mass adoption of the Nintendo Switch it would likely be wise on Nintendo's part to allow people to play all of their Nintendo Switch games on the new hardware.
If this report is accurate when it comes to the potential release date of a next-generation Nintendo console, then we could see an announcement of the hardware later this year, with a full reveal perhaps at a Nintendo Direct or at The Game Awards. It may be the case that the hardware is revealed first, with the company outlining how exactly this console differs from the Nintendo Switch, and why it's a worthwhile upgrade.