The Challenge of the Akeidah

(A re-post from four years ago. The comments to this post are especially stimulating. On an unrelated note - it's time that the museum had a professional website, including an online reservations system. If anyone is interested in donating their services, please be in touch!)
The akeidah never used to present any problems for me. About 15 years ago a certain rabbi claimed that Avraham failed the akeidah, and that he should have protested the order, just as he protested God's destruction of Sodom. I wrote an essay in response, in which I pointed out various significant differences between the two cases, as well as the fact that from Jewish tradition as well as the text of the Torah itself it is abundantly clear that Avraham was not considered to have failed the akeidah.
Over the last few years, however, there is a question that has really been bothering me. I've been studying various literature on the topic, but so far I have not come up with a fully satisfactory answer. My studies continue, but I wanted to share my question here in the hopes that perhaps someone can suggest an answer.
My problem is with the "happy ending" of the story, where God tells Avraham not to kill Yitzchak. Was this the inevitable ending? Is it actually entirely inconceivable that God would actually want someone to kill their son as an act of religious dedication?
Some claim this to be the case, and to be the message of the story. A teacher of mine once told me that God does not want child sacrifice, but He does want the willingness to do it. Rav Kook writes that there is a holy root to the pagan desire for child sacrifice, namely the willingness to give up everything for God, but Judaism demands this to be fulfilled differently. Shadal says that the point of the akeidah was to counter the claim by other nations that they are willing to sacrifice more than us. The akeidah showed that we are willing to make the ultimate sacrifice – but God doesn’t want it.
But if child sacrifice is immoral, and it is for this reason that God does not want it, then why would we be willing to do it? If it is entirely inconceivable that God would actually want someone to kill their son as an act of religious dedication, doesn't this mean that Avraham failed to understand what serving God was all about?
On the other hand, if it is not inconceivable that God would actually want someone to kill their son as an act of religious dedication, then why did the story end with God telling him not to do it? Wouldn't this give the wrong message and undermine the lesson?
I came up with another question that puts all this into sharper focus: What if God would have asked Yitzchak to kill Yaakov? What should Yitzchak have said? If he says no, then he is disobeying God, which doesn't sound right. But if says yes, then he is acknowledging that child sacrifice might be a legitimate way of serving God. In which case, why didn't God let Avraham follow through with it?
I have a possible approach, but I am not sure if it is satisfactory. We do believe in the principle of yeherag ve’al ya’avor. There are situations when fulfilling God’s command takes precedence over life. And obeying God’s direct command is certainly a higher religious priority than the three cardinal sins. Sometimes the right thing to do is to sacrifice life for a higher goal. The akedah teaches us that God does not normally set things up this way. That it is not generally a goal – except in certain specific cases where it may serve as a Kiddush Hashem, such as with the akedah. Maybe it can be said that it would be simply impossible for God to have asked Yitzchak to kill Yaakov, and that asking such a question is like asking whether God can create a stone that He cannot lift. Maybe it is truly inconceivable that God would want child sacrifice as a regular part of serving Him, but not that He might ask for it on a rare and significant occasion?
That's the best that I could come up with so far, but I don't think it fully answers the questions that I raised. I would welcome peoples' thoughts on this.