This grammar is typically used to express that once something has happened, the subsequent situation remains unchanging.
This form of kiri is only used with a verb in the past/passive tense.
きり is a particle derived from 切る(cut) that indicates that something happened but it did not thereafter follow the normal course of events and terminated. I am not sure that there is an English equivalent for this concept, but "that was it" comes close but not quite. Of course this type of expression cannot be used to describe 寝たきり老人. I probably have to say that the true sentiment behind this word is untranslatable into English.
You don't need the () for 'My son went to his friends house (and didnt come back)' because it is separately pointed out that he didn't come back in '帰ってこない。'
Unless 帰ってこない should be in ()'s.
in english dictionaries the part in brackets is what is implied, but not expressly written in the sentence as in ex608 but not ex845
The first exmpla can end 息子は友達の家に行ったきり。帰ってこない may be to emphasize the situation. Your Japanese is good!
「きり」here roughly means ずっと…している。…のままである。
No comment on my last comment?
() is absolutely for me(日本人）. He went to America is just the event in past when I translated the E-sentenc to Japanese and can't express the 「きり」without ().