Really depends on the leaks. Before the Dev Kits gets released, companies get a heads up to prepare for a more powerful system, and to our info
this happened in late summer of 2020. Considering current development processes, this would logically happen 3 years in advance, as current AA/AAA games have a 4-5 year development process - so the game is still in early development. Thanks to Covid, we can expect the successor was delayed by one year.
Early Devkits gets usually only sent out to First Party and trustworthy partners. Here it is unlikely leaks are happening and if, basically it is very easy for Big N Ninjas to track the culprit down. The current rumors e.g. are coming from Spain and Spain does not have many game developer who would be considered having a good partnership with Nintendo, so if true, it is most likely MercurySteam. I doubt Ninjas will be unleashed already for the currently leaked information, but wouldn't wonder, if the boss of MercurySteam got a call and also reminded his employees, how important the partnership for them is. Anyway, we can assume that they are/were on the trusted partner list, so get the console quite early. But we also know, that Nintendo is on the Gamescom (no surprise imo), but ALSO on the TGS and only in the Business area. As Nintendo notoriously skipping TGS, it is highly likely, that they are presenting there the final DevKit to Third Parties to attract them. If the Architecture is relatively similar to the Switch and/or the Toolkits are easy to handle, developer who planned well, can finish their game within one year. So yes, Late 2024 release is realistic to me.