I'm not going to summarize because summarizing and clarifying take up so much space that I don't answer the question.
long term thinking
A lot of times I don't realize that you really have to think very long term with unschooling. Even a high school student isn't really an indication of what the person's motivation and attitude towards Torah will be in the course of his or her lifetime, as an adult. I've seen many times where people pressure teenagers to behave a certain way or do certain things, which is somewhat absurd when you think that you are forcing a behavior temporarily, and in a few years, when the child is no longer in his parents' domain, he will do what he really wants to do. In that framework, it makes sense to carefully nourish lishma motivation.
skills vs ideas
I've mentioned before the debate amongst educators as to how much effort needs to be put into skills in an era where everything is online and much is translated. Think similar to the bygone era where people used to memorize, before the printing press made that unnecessary.
A lot of pressure of education is making sure that the children have skills, which is a lot of drudge work and repetition. If you are a parent who puts a strong value on your child acquiring skills, unschooling can be a risk. Personally, I am gravitating more towards the notion that the information is to a large degree available, and hopefully the desire to learn will eventually motivate a quick and efficient acquisition of skills, or else the child will eventually learn enough to acquire the skills in the course of learning. In that case, my emphasis and goals would to make the learning experiences pleasant and very interesting. And I would be inclined to wait for the child to show interest, instead of trying to coax them into interest.
seeding the values of the home and naturally things come up
I read an interesting article that was somewhat opposed to "radical" unschooling on a message board recently. It said that all the parents who say that unschooling works spend a lot of time crafting a wholesome, organic (in the sense of emerging naturally) environment for the children. Sure, the children eat healthily, since that is what is in the house. You present all sorts of interesting activities to choose from. But what about the kids who have TV and junk food?
Not to get off topic, I do allow unlimited media and although we have a lot of healthy food in the house and not too much junk food, we don't forbid any junk food. But that point did get me thinking about how unschooling is not a free-for-all. The parents DO have clear values and there are expectations about respect, living in the community of the family, living in society, behavior, and all sorts of things. In a family where Torah is a value, there are many many situations where Torah emerges naturally.
trusting torah to be interesting
I think maybe my biggest fear that my child won't be involved in limud Torah is founded in lack of trust. Do I not trust that the Torah is infinitely interesting? Do I not trust that learning is one of the greatest pleasures and satisfactions that a human being can experience? Do I not trust that the intricacy of halacha is a framework that leads to a better and more satisfying life? Do I not trust myself to be able to present the Torah as l'tov lanu, for our own good? Do I not trust myself to be able to convey that the Torah is delightful?
שָׂשׂ אָנֹכִי עַל אִמְרָתֶךָ כְּמוֹצֵא שָׁלָל רָב.