T r u e C r y p t
Free open-source disk encryption software

There is no company to go out of business. With open source if the project would be abandoned by its original authors someone else can pick it up or someone else can make a way to get your data back out of it.
I run all open source after being burned before. Imagine you made a simple database for your home insurance inventory in Microsoft access 1.0 and then 10 years later you need to file a claim and you find out that you can't get Access 1.0 to work on your current OS and import support for 1.0 was dropped a couple versions ago. You then have to search out and OS old enough to run the old version then search for the old version. I've been there and done that both for myself and clients who put important data into a closed source app and find out they can't read that data later.
I 1. stick wit open source and 2. do test restores of old data. to be sure I can still get it if needed.
I've been burned by MS access, MS Visio ,MS money and even had a couple old pfd's that wouldn't read in modern versions.