A lot of the replies so far are of the nature "if you did not care about the photo now, you won't care about it in 40 years", and "only a tiny proportion of what I shoot is really worth keeping". Let me articulate the OTHER side of the picture (pun intended) as someone who voiced questions about long term longevity of digital images (vs. negative and prints 'in shoeboxes') over 10 years ago...
- first issue is the accessibility of digital files (both JPG and RAW) 30-40 years from now due to the kind of media it is stored on...already I have documents stored 30 years ago on PC written to MFM ST-506 harddrives, which I cannot retrieve (admittedly I have not even tried because I have not needed these old documents!)...try to find an ST-506 controller that fits into a PCI bus in a PC today! So the data on the ST-506 harddrive is unavailable unless you put together an old PC with an ISA bus, to accommodate the ST-506 controller cards that you can still buy today. But then you have the issue of what media type you can transfer that data to, from ST-506 via what media, to store on media compatible with your current PC?!
- the next issue, as you have already brought up is the software that CAN handle the RAW files from 30-40 years earlier. We have seen this already happening!
- In June 2011, "For example, on the ASMP site at: http://www.dpbestflow.org/node/386

stated: "Images from some of the very expensive digital camera from the late 1990's are now only accessible
with very old computers." Later, on the same page, they list three formats that "are in at least some danger of
obsolescence in the foreseeable future": Kodak PhotoCD, Kodak RAW, and PICT.
"Two of these may be consider raw formats, Kodak PhotoCD and Kodak RAW. (PhotoCD because it was used to represent
scanned images, and no other intermediate digital format was used.)".
- In May 2012, someone writes, "Using a Mac OS X 10.5.8 with versions of Adobe Photoshop CS5, Adobe Bridge CS5 and Camera Raw Plug-in. Shot .CR2 raw format photos on my Canon EOS 450D (Same as Rebel XSi) Have always been able to open them successfully in Camera Raw and Photoshop. Now says that the files and/or my camera model/make is not supported by the Camera Raw Plug-in nor by my Photoshop."
So data loss is very real, it is demonstrated to be true. Does it matter? Some replies dismiss the issue as not truly of concern. But let me point out some examples of where it can be of concern...
- You die 50 years from now, and your surviving grandchildren and great grandchildren want to put together a photo montage of your life, to honor you at your funeral gathering. They want to access your lifetime of photography, so as to commemorate family events in your lifetime, but they are inaccessible due to reasons #1 and #2.
- (fictional) You ended up being one of the papparazzi who followed Taylor Swift, and she being a legendary singer later became a philanthropist who started a movement which ended racial bigotry in the world, so the historians wanted photos documenting Taylor's early life as a country/pop singer, but no one can get at your photos as they are inaccessible due to reasons #1 and #2.
- (fictional) You lived in a great coastal city NYC which fell victim to the rising waters of the oceans, and you photographed the city as it fought to save itself from flooding before it became 'Venice of the New World', and the photos were sought by historians and anthropologists who, in the 22nd Century, studied and documented society in the times of 'the Great Flooding of the 21st Century'. but no one can get at your photos as they are inaccessible due to reasons #1 and #2.
Yes, the photos no longer are of any value to YOU...that is not to say they are of no value in the future to anyone else. To think so is shortsighted, as if all of the relics of the dead that are cherished by anthropologists and historians all belonged to 'someone important'...no they belonged to Everyman.