Has Japanese syntax changed between the 1950s and today?


Excluding vocabulary items which are entirely new or have fallen into disuse,
what are some ways in which Japanese syntax itself has changed between the
1950s and today?

(I would also like to exclude phenomena such as the semi-productivity of terms
like ググる, since I'd argue these are new vocabulary and not fully productive
ways of deriving new words.)




[言文一致](https://en.wikipedia.org/wiki/Genbun_itchi) and the shift to modern
kana orthography (1946) happened shortly before this period, and they were
undoubtedly much more fundamental than anything that happened after 1950. But
I'll focus on the change of modern 口語 here. The list is far from complete; I
just wrote down things that came to mind.

  * Decline of ましょう as a way to express future inference.

> 明日は雨が降りましょう。

This was common in weather forecast until the 1970's, but we never hear this
today. See: <https://ameblo.jp/heppokomental/entry-12527905042.html>

  * Decline of some "heavy" keigo patterns (でございます, でありました, くださいませ, ...)

  * Continued decline of ぬ as a negation marker (ありませぬ, 分からぬ, ...)

  * Decline of many gender-specific sentence endings (かしら, だわ, ...), although many remain in fictional works as part of お嬢様言葉

  * Decline of most iteration marks (ゝ, [〱](https://japanese.stackexchange.com/q/40805/5010), ...) except 々. (If I understand correctly, these symbols have never been officially standardized nor banned by the government.)

  * Increased acceptance of ら抜き of ichidan potential forms (食べれる, 見れる, ...)

  * Increased acceptance of `i-adjective + です` (嬉しいです, よかったです, ...) and the decline of ～うございます. See: [Conjugating present and past negative i-adjectives](https://japanese.stackexchange.com/q/68964/5010)




[言文一致](https://en.wikipedia.org/wiki/Genbun_itchi) and the shift to modern
kana orthography (1946) happened shortly before this period, and they were
undoubtedly much more fundamental than anything that happened after 1950. But
I'll focus on the change of modern 口語 here. The list is far from complete; I
just wrote down things that came to mind.

  * Decline of ましょう as a way to express future inference.

> 明日は雨が降りましょう。

This was common in weather forecast until the 1970's, but we never hear this
today. See: <https://ameblo.jp/heppokomental/entry-12527905042.html>

  * Decline of some "heavy" keigo patterns (でございます, でありました, くださいませ, ...)

  * Continued decline of ぬ as a negation marker (ありませぬ, 分からぬ, ...)

  * Decline of many gender-specific sentence endings (かしら, だわ, ...), although many remain in fictional works as part of お嬢様言葉

  * Decline of most iteration marks (ゝ, [〱](https://japanese.stackexchange.com/q/40805/5010), ...) except 々. (If I understand correctly, these symbols have never been officially standardized nor banned by the government.)

  * Increased acceptance of ら抜き of ichidan potential forms (食べれる, 見れる, ...)

  * Increased acceptance of `i-adjective + です` (嬉しいです, よかったです, ...) and the decline of ～うございます. See: [Conjugating present and past negative i-adjectives](https://japanese.stackexchange.com/q/68964/5010)

