Synthesized answer
The provided passage [Passage 1] does not specify what questions remain unanswered.
It does state that the work "How to do things with words" sets out Austin's conclusions in a field he worked on for at least ten years [Passage 1]. The passage explains that Austin abandons his earlier distinction between performative utterances and statements, and instead proposes a more general theory of 'illocutionary forces' of utterances [Passage 1]. This new theory has significant implications for various philosophical problems [Passage 1]. However, the passage does not detail any specific unanswered questions that arise from this work.
Synthesized from the book passages below. Chat with the book on Feynman for follow-up.
From the book
Title: How to do things with words by J. L. Austin Description: This work sets out Austin's conclusions in the field to which he directed his main efforts for at least the last ten years of his life. Starting from an exhaustive examination of his already well-known distinction between performative utterances and statements, Austin here finally abandons that distinction, replacing it with a more general theory of 'illocutionary forces' of utterances which has important bearings on a wide variety of philosophical problems.