Definitely not sarcasm.
An issue still remains for me though: this interview is almost a year old. And the state of the union address (which was also very good) was almost 7 months ago. If he has another strong speech or interview soon, I will be completely reassured.
A strong second debate would be awesome too, but I see no reason now for Trump to agree to another one.
If you can give a reference to any such book, I’d be very interested to see it.