These are all concerning avenues for users. Adding advertising tends to mean user privacy is compromised, as ads become increasingly targeted by the day; shutting a company down means all user data gets removed, and it's up to each user to find a new product or service to fill the hole. Rinse and repeat.
Arguably worse is when the company and all attached user data is acquired. There's very little control any user has over that decision: they may like the original product, but are uncomfortable with the new owner. These decisions are impossible to foresee: if you signed up for Flickr ten years ago, or Tumblr five years ago, would you be expecting your photos and blog posts to end up in the hands of Verizon today?
We see the same thing in education. Hopefully, a vendor is successful and things go smoothly. But, corporate (or open source) failures, acquisitions, or changes of terms will all impact what happens to student data.
We need to make sure we own our data, or at the very least have workable backups and/or exports that can be quickly spun up if things go south.