A couple of thoughts re the original question (11 yr plan) and some of what's been said in the posts above:
-- I think people are different. Some plan, some don't. Some have short term plans, some dream longer term. I was a long term planner. I started dreaming about it 20 years before I bought the boat. I was "in the market for the boat" vicariously for 15 years before I bought it. The dream provided a focus, a reason for saving, a motivator for learning (mostly through reading, but also lots of sailing on OPBs -- other people's boats. I don't know if I'd have gotten to 'live the dream' without the planning.
-- Trying it first is a good idea. Even if only a few weeks of chartering now and then when the budget can afford it. You'll quickly get an idea of who's dream it really is. My girls didn't like it -- one stayed in her cabin and read all the time. Initially, my wife did it only because she loved me. Later she would confide that she came along because she'd met a lot of second wives on sailboats (first wife didn't share the dream). About ten years into the planning for the great escape, I learned it was really my dream, not theirs. So, I adjusted the long range plan accordingly -- we waited until the kids were through college, we started cruised locally several summers before going away to get my wife comfortable, we spent two years in the Caribbean poking around for more comfort building. Eventually we discovered my wife didn't like long offshore passages (she's done several, including an Atlantic crossing, but as she keeps reminding me, it's not her dream). I now know that when long passages are in the plan, I needed to find crew and airfare for my mate.
-- I never met a "boat kid" who was anything but well adjusted, smart, engaged in life, confident and interesting to talk to. Great kids, every one of them. Family cruising seems to be a great experience for kids. They learn a lot about life and themselves. They become real contributing members of the family's endeavous far faster than would it they lived ashore. It is true that it's hard to uproot teenagers, but if they're up for the program, they will probably do fine. Most boat kids I've met are probably younger than yours at the time you're planning to leave, but there are a few teenagers out there. All that said, it's important that the kids want to do it -- that it is their dream, too. If not, you'll all probably be miserable.
-- If at all possible do not sell your house. Find a realiable realtor to monitor tenants and a good handyman to look after things while you're gone. Expect problems, but don't think you'll eliminate all the problems by selling the house. First, you'll have to buy back into the market when you return. Consider how you'll do that -- boats generally don't appreciate in value and cash on hand tends to get spent. Second, think of the house as an insurance policy, a safety valve -- a place to run to if something goes wrong. What happens if someone develops an serious illness in year two and you need to be near medical care on a full time basis for a while? Where do you live? The house can be a psychological comfort to members of the family. Just knowing that they can "go home" helps them "go on".
-- Keep planning (and dreaming)! But stay flexible in how the plan evolves. Anticipate potential problems, work out solutions. And recognize that in the end, it won't be exactly the way you planned or dreamed it would be.
It will be better!