To deb or Snap or Flatpak?

[kalpana]

I have a number of non-techie neighbours/friends I support who use Ubuntu. For those who do not want any notifications about updates I have been looking at the three main delivery package methods. Personally I use deb and have a number of ideas how to make deb apps update themselves without user awareness. I have been frustrated with both snap and flatpak, largely around the inability to be able to establish a test environment to try out different methods of background updating (e.g. not easy to get previous versions of Chromium). My question is the long term viability of, mainly firefox and chromium/google chrome, deb packages. I tide seems to be turning re snap - will there be a time where the deb package for an app is no longer available? I think the answer is Yes - "it is foolish to rely on, say, firefox or chrome debs being continually updated". At the moment I feel snap or flatpak do not meet my requirements (100% no user involvement re updates - it all happens in the background). How will we know when a deb package is no longer being maintained/updated and the need to switch to snap/flatpak has arrived?