I'd like to add to this that since the app lets you export your content, even if/when Roam dies, it would still be possible to move the data to another app somewhat easily.
Usually these end with an "Our Incredible Journey" post[0] and 14 days to back up your data, with the site half-broken during that time and nobody manning the support. I'd set up a script to keep your data backed up if the notes are important, or pray you're not on vacation when they get acquired.