If it's just for storage / backup - then dedicated cloud backup might be a better alternative. Something like Backblaze, or possibly even Dropbox might suffice (Though Dropbox shouldn't be used as backup really) and this would also backup anything else you want.
I use SmugMug (who actually acquired Flickr) for sharing photos semi-privately - you can mark albums as public/unlisted/restricted depending how easily you want people to find your photos. You can also sell from it if you're that way inclined.
As with all things free, I don't personally think you can complain when it gets removed with plenty of notice. £4 p/m is pretty cheap for that quantity of storage IMHO (it's cheaper than Backblaze for example) - though no doubt their main motivation is to free up server space. There's a LOT of people using Flickr for free image storage.