I think this is a bit unkind.

Maybe: Storage is expensive, and we'd rather collect money from you, rather than sell you to advertisers.

I think you nailed the marketing of this change. Though, if Flickr posted the steps/goals to making the user a "priority" rather than a "product," I would be more convinced. A cursory read of their TOS doesn't indicate any changes (though this may be premature as the changes are not in effect), and their (1)non-blog upgrade post doesn't seem to indicate any changes in data collection/selling.

As an aside, if you were looking to subscribe to their Pro product, the link in the blog post contains a coupon for $15 off their yearly subscription.

1. https://www.flickr.com/lookingahead

Are we sure they still won't sell you to advertisers in addition to subscription fees?

I promise this won't happen. I hate customer-hostile business models. (Disclaimer: Blog author, CEO & Chief Geek here)

your own cloud will cost you less and it will be much safer privacy wise until these smugs change their ToS again and throw you over deck

Well, yes. This is the internet growing up.

Servers cost money. People making the software and running the servers cost money. Previously those costs were hidden from end-users, usually by advertising-based business models. Now that consumers aren't putting up with that as much, smart companies are doing the old-fashioned thing of charging people for the valuable services they provide, instead of selling off human attention to advertisers. On the whole, this kind of stuff is better for everyone.

A bit harsh, but... yeah, companies need to make money, and it seems like flickr is going about that in the right way here.