So before the crying and gnashing of teeth stage. If you don’t have copies elsewhere it is time to make sure you do. Backup those on-line photos now
Bulk Downloading from FlickrNo so long ago you would have had to do it one photo at a time or better still one album at a time (look for the download arrow icon). Now with this the new camera roll feature it is even easier. You can just select all (which does select all your photos, so definitely don’t press delete, the red rubbish bin on the left hand side) on each grouping the the camera roll. You can then move onto the next grouping and press select all again, which add the new set to the selection bar at the bottom of the screen. Normally the camera roll is order by date (either taken of uploaded) and this is a good way to structure your downloads, say my month or by year. However remember if you have uploaded a lot of images it can take a fair while to download a really large collection and it might be wise to break the downloads into logical groups. If you are more interested in organizing your collection by theme you can consider using the magic view to help you select batches of images to download in thematic groupings (there may be a few miss-classifications).
Bulk Downloading from Google PhotosDespite the promises about recognizing how much work people have put into saving and organizing their photos in picasa. Google have been quiet about how to save any on-line uploads from Picasa into picasa web albums. The picas web photos are still on-line but now they are in Google Photos. However finding where to download them is no longer as simple as finding the download to Picasa button. Both the the individual and album views have three vertically arranged dots in the upper right corner, which signify more options. Clicking on these dots brings up an action sub-menu which contains the download feature. It the case of albums it is a download all. I haven’t found a way to selectively bulk download. If you are using auto-backup the photos will be grouped by date (each date will be its own album)
Remember :: It is the right time to Backup those on-line photos now
PS (May 2016) I have discovered you can bulk download everything using google's takeout service