When My Photo Stream is shut down, will all of my photos remain in my Library?

Photo Stream only holds photos taken within the last 30 days. Unless you took all those 549 photos in the last 30 days they are not in the Photo stream. It automatically removes old photos and uploads new ones.

Photo Stream is never the sole location of photos. Anything in the Photo stream must exist physically locally on a device too for where they were uploaded to the My Photo Stream.

If one device takes 10 photos then those 10 photos would upload to the Photo Stream, but are also stored locally on the device or even in iCloud Photo Library if that option is also turned on. Other devices may access the photo stream and see those photos, but may not have said photos stored locally. You can download the photos to a device that does not have them stored locally as follows:

1. Open Photos, then open Albums.
2. Tap My Photo Stream, and then tap Select. 
3. Select the photos you want to save.
4. Tap the Share button, and then tap Save Image.

Best way to guarantee that you're not going to lose anything is to go into Photos, hit "Select All", and then select the "File/Export/Export Photos..." menu item. Select an external drive for your destination and let it rip.

After that's done, dismount & unplug the external drive, put it on a shelf until after the Apple transition is complete (to be safe, assume 1 Aug). We were all meaning to make an external copy that we could airgap and take off-site anyway.

FYI, some easy & (mostly) free places to store physical backups include:

• a desk drawer at work
• safety deposit box at your bank
• a relative or friend's house

Not possible. My Photo Stream cannot hold photos past 30 days.

Are you sure you are looking at the Photo stream? Where exactly are you seeing these photos?

The Photo Stream album is a specific album different to the Camera Roll or Recents album.

I have an iMac which is different to an iPad or MacBook. All my old devices with Photo Stream have photos which are years old not just weeks so dont feel your comments are correct. On my iMac I have photo stream and library on my mini iPad I have photo stream and camera roll so I am certain I know what I am looking at?

Yes. The My Photo stream shutdown will only affect photos in the Photo Stream.

Locally saved photos on your Mac will not be affected in any way.

How can I garantee that all (549) my photos in my photo stream are in my library as I dont take pictures with my iMac?

The photos in my photo stream go back to November 2019 so how can that be?

Same here I tried and it did the same deleting the photo in my library------- can it be that Apple are set to delete everyones photos off there device's