Had Elvis pulled through on August the 16th I would like to think that it would have been the wake up call that he needed to take stock and have a look at where his life was heading.
That said Elvis had already had a couple of close shaves prior to this event and was in complete denial about his addiction. The difference this time could have been the publication of "Elvis What Happend" and the future screening of "Elvis In Concert" I would like to think had Elvis been around to see this footage a lifestyle change would have been iminent. In my personal opinion Elvis had lost touch or simply wasn't aware of his condition, or more to the point the severity of his condition due to his terminal apathy at that time.
Elvis had ups and down during the latter part of the 70's and when he put his mind to it could easily put right the wrongs, you only have to look at October 1976 to see Elvis in good shape. Elvis was a very private man and the publication of "Elvis What Happend" was a watershed that knocked the stuffing out of him, had he got passed this I think things could have turned a corner.
Elvis needed to be challenged both personally and professionally, unfortunately I don't believe those around Elvis were up to the task, thus ensuring that if it hadn't been August the 16th it would have only delayed the inevitable to some time in the future
On a optomistic note, did he really die