So, the difference between the internet and the minitel is nothing like the difference between Nextcloud and American alternatives (Dropbox & Co).
everything was 'based on another protocol' before x25 :D
i think that just like Minitel was one of many services that used the banal packet switching tech at the time, nextcloud is just another banal cloud offering. What is interesting is what will happen soon: truly distributed networks will be for [aws/nextcloud/etc] what the internet was for [minitel/dec/telenet/bbs] users.