I was one of those that was able to still buy single image downloads. I was cut off last week without any notice and also wasted considerable time trying to figure out the issue at the last minute. Shame on Adobe for their lack of understanding of the importance of notifying customers.
Branching into a new discussion
I understand the scenario here and I apologize for the miss in notification but while we have moved away from single purchases of Standard assets, our customers are still able to purchase a collection of assets including video, 3D, templates and Premium images on an on-demand basis. The most flexible option is to buy a pack of 5 credits, which can be used to license 5 standard images any time over the next 12 months (or 6 months, if you’re in Japan).
Please see Stock FAQ: What are Credit packs? for more details.