Ahh so it's clear we don't have a clean solution to this at the moment.
Having a forum's own image hosting service would be ideal, but yes it would require significant investment in terms of time, money, and effort.
To be honest I think doing nothing shouldn't be an option here... we have to do something
3: Exempt imgur links from the image proxy so they all just work. But this has privacy implications, since imgur will see forum users' IPs. Also, imgur has apparently banned a lot of Tor exit nodes etc. as well, so imgur images won't work for everyone.
Big No!!! Leaking ip to imgur might be ok to some users but this could potentially be manipulated and exploited, I mean "nobles" will find a way to put their own urls, which might lead to user's IP tracking.
4: Exempt imgur links from the image proxy as above, but prevent using imgur embedded images in any future posts, to sort of phase it out.
Isn't it the same as option No. 3? How will it work? I mean If I go to my old post and try to edit, will it allow me to save without updating the imgur link? If not then it's another headache for the users and if yes then the same risk of IP leak is there.
So technically speaking, option 3 and 4 aren't the same?
2: Make it so that all past imgur embedded images show up as a clickable link instead of as an embedded image, as if the poster had just posted the imgur link instead of using the [img] tag. I could also maybe make it so that if you click the link, it will JavaScript-expand into an embedded image (using the specified width etc.) without going through the image proxy.
This seems more appropriate solution from all the options presented, convert all the imgur [img] tags to clickable links.
Further I don't know how this "
without going through the image proxy" thing will work? I'm afraid it might have a risk of IP leak too, as you mentioned in option 3.
For those who really want their images as it was, they can just use TryNinja's script. Seekers will find their solutions today or tomorrow.
That script is limited to active users only and even among those users, I have doubts that less than 50% will be aware of its existence or actually execute it.