Duolingo is a leading name in online language learning, but it's still a small company with big dreams -- how far can it go in the next five years?The language-learning company Duolingo (DUOL 1.41%) launched in 2012. Duolingo's mobile app is currently the third most popular app in the Apple App Store's education category, ahead of popular learning resources such as Instructure's Canvas platform and Alphabet's (GOOG 1.28%) (GOOGL 1.58%) Google Classroom. On Alphabet's Android Play Store, Duolingo sits at the ...