The only Apple devices that Apple has ever consistently updated has been the iPhone and the Apple Watch (and the Apple Watch Series SoC packages have barely been updated in the last 4.5 years).Ok, so it's not so much that Apple is releasing 15 "new devices". Rather, it's that Apple is going to provide scheduled updates to all of its existing product lines, exactly as it has done every year for the last decade and a half.
Apple has very frequently let their hardware rot on the vine. Sometimes it was because Intel didn't have *quite* the right chip Apple wanted, but often it was Apple just not wanting to invest in new hardware if it wasn't going to make it up in more sales volumes.
Even after the ARM transition, we've seen Apple let hardware rot, like the M1 iMac, which Apple could have updated, but chose not to. Apple couldn't even bring itself to replace the M1 MBA with the M2 MBA, leaving the M1 MBA in the line-up.
Maybe Apple will change, but right now I would bet on Apple continuing to periodically letting low-volume products rot on the vine, because that it what Apple does over the past 20 years.
It's also plausible that the M3 Mac Studio and Mac Pro might not even come out until 2025.