If the family data plans do happen and if they are not to pricey then I would probably get it. I have 5 phones that have unlimited data right now on special promo pricing ( $20 discount to each phone line making the unlimited data only $9.99) . This special pricing ends in November :'( . So I'll either look for the family data plan hopefully in place by then or its back to dumb phones for my kids

. Cause I can't afford that much dough. Pay enough as it is!
Also if I do end up getting the family data plan, I would just teach my family to use our wifi whenever possible. Plus, get them in the habit of disabling their data when not in use. I think with practicing those kind of habits anyone could get by on a shared data plan and not be a data hog. Just my 2 cents.