We might get a repeat of the PS2 timeline (the first PlayStation with a Slim naming, but the PSOne model of the PS1 was technically a slimmer version)
PS2: 2000 PS2 Slim: 2004
PS5: 2020 P55 Slim: 2024
But if we get a repeat of the roughly 3 years for a Slim that we got with the PS3 and PS4, then your expectation will prove correct. But we have to look at context.
PS3 got a Slim in that time period because the PS3 was not working out and they needed a shift. PS4 got one in that timeline because the PS4 Pro came out around the same time (2 months later than the Slim) and Sony didn't feel like having 3 models.
Launching a Slim in 2023 makes some sense, but doesn't make as much sense as 2024.
If Sony see's that demand won't be met for years yet without a Slim, then they need it asap.
If Sony see's that demand will be met by or near years end, then they need a cheaper Slim asap.
If Sony see's even more inflation or some type of downturn coming, then they need a cheaper Slim asap.
If they don't see any of this on the horizon, then I'd agree, there's no need to rush it before 2024.