I think they have appeal as ANOTHER doll, but I don't think they are going to take ovr from the barbies. The main thing about barbie is that it is now a brand in itself- there are barbie cars and dream houses and ponies and planes and pets and bloody pizza ovens.... Including a TV series now.
I think maybe in 20 or so years when the lottie doll is able to expand into that much of the market (which obviously would be extremely hard to do considering the niche in the market previously exploited by barbie is now an oligopoly of various monster highs, lotties, sindies, ever after high, equestria high I could go on and on and on) then it may be able to compete.
I agree with the principal of the lottie doll, I do... I just don't think it's on th end of world domination- or even small child domination!