Avraham might have psychologically softened the blow of dealing with the akeidah by telling himself that even if he sacrifices Yitzchak, all is not lost. If he could miraculously have a son at 99, why not at 136, or even older? However, the Sefas Emes explains that Hashem told Avraham up front that that’s not how it’s going to work. Kach na es bincha es yechidcha… Yitzchak is the only one – there is never going to be a replacement.
An increasing number of Judaica books are devoted to “hashgacha pratis” stories, stories of people who sacrifice for the sake of Torah and mitzvos and are rewarded with things working out better than they could ever have expected. I have no problem with these books so long as they are shelved properly in the fiction section. I say that not because the stories are false, but because the idea that Hashem will necessarily reward sacrifice and commitment and make things work out is false. The akeidah is the paradigm of sacrifice. It was done with the understanding that there will be no happy ending if Yitzchak is sacrificed, no way to reconcile his loss with the promise of lineage that will carry on Avraham’s tradition.