On February 26th, Kindle customers will lose the ability to download eBook purchases directly to their PC. If you want to switch to a rival eReader brand in the future, I suggest that you use the soon-to-be discontinued “Download and Transfer via USB” feature to archive your Kindle library.
It’s not what happened when they removed 1984 off of people’s Kindles. I think somewhere in the fine print, they’ll probably have a clause that says they’re allowed to do that.