You wrote: "The very self that wills is the self that needs sacrificing. Can the self sacrifice itself? I don't think so...the self...needs to be sacrificed by something greater than itself call it the soul if you like." Quite right! If one assumes we are on our own.
On the other hand, most Christians (including me) believe God sacrificed himself unto himself precisely in order to provide a way for each self to be made anew. God did what we cannot do, and made it possible for us to participate in his kind of self-sacrifical life. So...from my perspective it is possible to grow toward "agape," precisely because God has chosen to make it possible. It's certainly not easy. In fact,it usually hurts. "Take up your cross and follow me" describes the experience.
My hunch is that our individual perspectives on God undergird what seems to be a genuine difference regarding our potential for self-sacrificing love.
On to your question: "What is your take on the connection between honoring our parents and living well on the land?" I think other standard translations read "live long in the land." I start with an assumption: the commandment is part of a package of injunctions designed to form a particular kind of community. In this case, God's intent is that his people provide care for their aged parents. The commandment may apply to the individual son or daughter or to the community as a whole.
Assume the commandment was given while the Israelites were in the wilderness. If so, the temptation to discard elderly persons who could not keep up or who consumed valuable food and drink must have been quite real. The commandment might have had immediate application: "Let the community slow down, let all make do with less, that none--including the declining elderly--may go without what they need to live."
The temptation to discard the elderly did not go away once the community settled, though it may have taken other forms. In either case, the commandment assumes a stable community cannot be built and sustained if the weak are neglected or cast aside.
I tend to think the commandment has special relevance for modern society, with its strong emphasis on production. What are we to do with people who can no longer produce more than they consume? At the least, our society, including the church for that matter, tends to want to hide them. The commandment directly challenges our tendency to measure another's worth in terms of production. In fact, it suggests our worth is directly proportional to how well we care for the elderly (and by extension, the weak in general).