微软那推说的应该是XSX对初代Xbox和Xbox360的兼容和现在的Xbox One一样

然后兼容所有的Xbox One游戏

查了下现在的兼容列表里初代Xbox和Xbox360游戏一共有607个。有美版Xbox One游戏一共1696个。
https://www.xbox.com/en-US/games/xbox-one
https://www.xbox.com/en-US/xbox-one/backward-compatibility

相比之下 PS5如果只能向后兼容100个PS4游戏的话，确实差距有点大。

引用:

原帖由 wjl1023 于 2020-3-20 10:12 发表
posted by wap, platform: Samsung
没说100个，基本都兼容

确实Reddit上也有人提到，Mark Cerny的原话是：“Running PS4 and PS4 titles at boosted frequencies has also added complexity. The boost is truly massive this time around and some game code just can’t handle it. Testing has to be done on a title-by-title basis. Results are excellent, though. We recently took a look at the top 100 PlayStation 4 titles as ranked by play time and we’re expecting all of them to be playable at launch on PlayStation 5. ”

所以可能确实大部分都能兼容，只是需要索尼逐一测试。

但PS Blog上写的是：“Lastly, we’re excited to confirm that the backwards compatibility features are working well. We recently took a look at the top 100 PS4 titles as ranked by play time, and we’re expecting almost all of them to be playable at launch on PS5. With more than 4000 games published on PS4, we will continue the testing process and expand backwards compatibility coverage over time.”

意思就是首发时应该只有这100个左右兼容了，后续再说。

所以至少首发时应该只能保证这（差不多）100个兼容，否则PS blog没必要这么写。