TIFF is a classic storage format, but PNG is common for web images and isn’t going away either. DNG is for RAW sensor output from professional cameras and is not used for edited and published images. However if you’re archiving your photo collection or something than keep the DNGs!
I guess I can talk a bit about the first and third points for my personal archiving (certainly not on a global scale).
For data storage data should be regularly be checked for bitrot and corruption, preferably with a file system that can heal itself if such a situation occurs. Personally I use ZFS RAIDZ with regular scrubs to sure that my data is bitperfect. Disks that regularly show issues are trashed, even if they appear to run fine and show good SMART status. For optical disks in a safe or something I reburn them every ten years or so even if they’re still readable to keep the medium fresh.
I’ve actually known someone who had to painfully setup a Windows 95 computer in order to convert some old digital pictures from a equally old digital camera stored in a prop format. Obviously that’s a no go. For my archives I try to use standard open formats like PNG, PDF, etc. that won’t go away for a long time and can be reconverted as part of an archive update if the format starts to become obsolete. You can’t just digitally archive everything and expect it to be easily readable after a hundred years. I don’t do this but if space is limitless lossless format could be used (PNG for photos, FLAC for audio, etc.) so any conversions remain true to the original capture.
Well we are one of the largest instances out there with open signups…
If everyone links to their blog instead of writing a text post I think there will be issues with self-promotion and clickbait like you said. Also people might be running ads/etc. on their own blogs which adds a monetization side to it all (i.e. I want to attract people in the magazine to click my link and see my blog so I make more money).
On Reddit for instance if someone discusses an interesting concept or reviews a product in a self post the sub appreciates it a lot. In contrast if someone posts a link to their blog with the same content it’s generally less well received.