Among those listed, Slack is the biggest existential threat (or complementary partner). The others can't even speak the language Dropbox's customers speak. >

Among those listed, Slack is the biggest existential threat (or complementary partner). The others can't even speak the language Dropbox's customers speak. > their main strength seems to be that they have the best cross-platform UI/UX right now and they will continue until Apple treats Android as a first-class platform, or Google treats Windows as one, or Microsoft figures out who they are anymore.