It definitely seems that Yamaha has hit the brakes on the development of many of their keyboard lines. Some of it could be Covid-19 related, but not all of it. Normally, a replacement for the PSR-E463 would've been out earlier this year, and therefore in development before the pandemic, but so far, not a peep. The newest higher-end portable keyboard on their US website is the PSR-I500 -- an Indian music based offshoot of the E463 (though it does include some interesting features that I want to check out). As far as I can see in the photos, it uses the same shell/housing as the E463 but just has different functions for some of the buttons.
I would've expected replacements for the PSR-E263 and E363 last year, but all we got was the PSR-E273 this year, and nothing else.
And of course, as noted above, the PSR-S670 is now 5-6 years old. It was preceded by the PSR-S650, and when the models ending in "50" were replaced with those ending in "70", we got the PSR-S670, S770, and S970. But since then, the higher models have been replaced twice, with the S775 and S975, and then the SX700 and SX900, while the S670 continues unchanged.