There are a lot of services that come as go these days. Putting it in Robert Frost’s style,
"Services may come and services may go, But users may go on forever"
Some services get bought when larger companies go shopping and may become many things, sometimes even dead. Some others just shut shop when their time is up. I have very high respect for people running services (useful or fun) that put a smile on peoples faces. When they get bought they make some cash - maybe just enough to get compensated for the time spent. Good for them. But the other side of the story: the people running these services know that
I don’t see these people doing much about it, other than just saying “You can download your data”. But that doesn’t discount the fact that these users spent their time entering data to your system. What do I do with the data. Data is useless without something to that operates on it.
APIs, exporters, do what you can to help the users out.
Try to partner with your competitors and help them with integrating your APIs to import data. Minimize friction so that users who want to move, are able to do it without much pain. Ideally, buttons that say “click to move to Service-X” would be very pleasant. I’m sure a lot of your competitors will be happy to help you out with this.
It’s very likely that you launched with beta period and flaunted your invites. When you shut shop, give users the same level of royal treatment. Shut down slowly but provide proper support. This is the period that your support has to be super-active and very helpful. They trusted you and your team when you launched, now it’s time to give back.
In India, when your guests are leaving, it’s considered bad/arrogant to close the door, when the guests are still just outside your door. So you’ll usually notice that Indian hosts wait until their guests are out of their sight before their close their door. I consider users my guests, so they get the same respect.
If you are running a service, that you aren’t sure you’ll be running for a long time, call it what it is - an experiment.