I feel that I understand what you're asking. You're asking, isn't R' Akiva's statement trivial, because it does not rule anything out? If this happens, then this is for the best, and if that happens, then that is for the best. But anything can still happen.
You're going to find that many of the truths we cling to depend greatly on our own point of view.
Some children struggle in childhood with the perception that our hopes are often disappointed. And sometimes they progress to a child's faith: although lots of hopes are disappointed, our most important hopes in life will be realized. We sometimes try to encourage this child's faith at bedtime.
On the day the rooster died, Rabbi Akiva observed that things always go our way. Misfortune doesn’t disprove this. Anyone in his position might have been sad about his losses until he discovered that those supposed misfortunes were hugely advantageous to him. If he had instead survived that day by 100 years and died without ever learning that the town had been captured on that day, he might have remembered the day begrudgingly as the day when he received less than he deserved; but that is only possible for any of us because we remain ignorant of the good in everything that happens. Instead he did learn of the town; but unlike many people he reflected on the fact that for that event and for every event there are limitless consequences of which no person can ever become aware. In other words, the lesson was not just that the best course sometimes contains some costs; the lesson is that if we knew the truth we would not consider the costs to be costs at all. But we never know the truth.
If the people of the town died before they discovered how their own deaths were for the good, that does not distinguish them from the imagined Akiva (who never learned about the town), or from most of us who live and die without understanding the good in all of the things that seem so terribly sad about life. The only important difference is in our ability to imagine that this is so.
I know a family whose life unfolded in such a way that looking back on it, I am sure that it would have been better if one of their number had died years ago. But if that person had in fact died, then of course nobody would have been in the position to understand how this death was for the good of all concerned, including the good of the decedent. Instead, the surviving members of that family would have been emotionally devastated by the death, suffering terrible pain and terrible doubts about providence. That is the position which we have put G-d in: he must treat us with such gentleness or harshness as He knows best for us, given that we differ in our trust in him and our consequent ability to accept harshness. Because this family could not have accepted the death which would actually have been for the good, they instead saw the consequences of their lack of faith. The distinction in R’ Akiva is that he understood this.
I am a privileged member of a privileged society. I've known only peace and prosperity, and health and education receive more public support than most societies could have dreamed of. Yet I have a friend whose child died in her grade-school years. I have two friends who fled their burning homes; in one case the house was completely lost. I have friends whose children have profound handicaps, friends who have been victims of crimes, and so on. So I suspect that not many adults at any time in history entertained a child's faith. But some of us, including Rabbi Akiva, have entertained the faith of an adult.
Consider Rabbi Akiva's story. He saw thousands of his students die (Gen Rabbah 61:03, Ecclesiastes Rabbah 11:01, Yevamos 62b3). Then many of his colleagues were brutally killed during the savage Roman persecution of the Rabbis, the martyrs recalled in the Tisha Be'Av service (in Kinna 21), in the Yom Kippur service (in Eileh Ezkra, on p. 266 in Chabad's new bilingual edition), in Sanhedrin 11a3 #29 to 31, and in various other places. As Rabbi Eli'ezer had warned (Sanhedrin 68a1, cf. Pesachim 69a2), Akiva's death would be especially terrible (Berachos 61b, Yerushalmi Berachos 93b3 in the ArtScroll English edition).
And as they were combing R' Akiva's flesh with iron combs, he recited Shema.
So you ask: Does Rabbi Akiva's statement rule anything out?
And I answer: only despair.