I wouldn't say that they've avoided marketing, they're active on Twitter. I made the switch over a single day by sending a message to all my contacts informing them about it and then proceeded to delete all contacts from my list. The people I speak to regularly were quick to switch, others have switched over the months. I still have to use Skype from time to time for conference calls with certain people, but I avoid it as much as I can and don't consider any conversation I have on Skype as private.

Wire has also open-sourced their clients and a lot of components, so even if they were to vanish as a company, all work is not lost.