The reality is that paid services are not immune to be shut down, for example after an acqui-hire. See Astrid, Sparrow and many others.
Heck, even services backed by a web giant like Google are not immune either, they can always decide to shut it down like they did with many of their services.
Heck, even services backed by a web giant like Google are not immune either, they can always decide to shut it down like they did with many of their services.