New shortcut update, lost files?

Hello. I havnt updated to the new keyframe feature and was wondering if i do that, will my MLT-files not be able to work or will they work once i have downloaded your new update? Im afraid that if i update, all my stuff that i have saved will be lost. would be preciated if you could answer. This is what i mean

You can open your mlt files with the latest version and they will work. But if you save the mlt in the latest version you might not be able to open it in an older version you can open them in an older version but some effects might not work as they used to.