No format is immune from future displacement. Flash is an interesting example of how one maufacturer can attempt to displace a deeply entrenched format. All you can do is pick a format for backups and if the software you are working with no longer supports it in the future, use a converter to change files to a format it will play well with.
Myself I keep raw format of everything. After editing, I'll create JPEGs for any printing I need/want so I can reprint easily if needed without having to duplicate work done once. For electronic submissions most clients prefer to receive JPEG, so I create JPEG files which are archived, in addition to the raws, for potential resubmission. If re-editing is requested, it is back to the raw file and creating a new JPEG of the result for submission and archiving to preserve the full revision history. This is a system that seems to work well for my needs. Other people will have different methods for managing their evergrowing gigabytes of files which suit them. It really is a matter of personal preference and workflow patterns.