Samsung isn't the only Android manufacturer. Comparing Apple sales to flagship Samsung sales is pointless. Sure, Samsung sells the most Android powered phones.. but to compare Apple to Android sales you have to look at every brand that sells an Android powered phone. Even if you just want to compare high end phones you have to include HTC, Motorola, LG, etc. They all have high end phones.
Back on topic, Windows Phone if it ever took off could probably dethrone Android. And Microsoft better hope that they do because they are running out of time. Android is looking pretty unstoppable right now. And no way will iOS ever be the #1 mobile OS just because it's too locked down. It may do better in some countries but for at least the next 5 years I'm betting on Android. Especially with all the cheap phones out there. Apple will never make a cheap phone. You can already get an iPhone4 for free with a new contract, doesn't get much cheaper than that.