Nobody can guarantee that, but it's open source so you can always do it yourself. I would be more worried about Evernote, Dropbox, Google Calender and other pro

Nobody can guarantee that, but it's open source so you can always do it yourself. I would be more worried about Evernote, Dropbox, Google Calender and other proprietary solutions, because if they decide to close the service, there's not much you can do about it.