Given that imgur seems to be accesible again (for the time being at least) but for the images that now or in future are no longer accessible I think using Option #2 would be a way to simply get it over and done with and let the past be the past.
If imgur will provide an error for future uploads it puts the onus of the member to select an image hosting website which should serve the purpose and also keep a back up of all images uplaoded from now onwards.
It looks like imgur is no longer blocking the image proxy. I didn't change anything on the forum's end, so imgur must've loosened up their limits. I guess it's not necessary to convert img images into links as long as imgur keeps working. But to prevent this from happening again, you'll get an error if you try to embed imgur images in posts from now on.