I, personally, am not convinced. However, I don't think the theory that he will drop a new one each week until Wondercon is completely outlandish, either.
The timeline does fit:
There are/were 6 weeks left til WonderCon from when the Aquaman pic dropped. So he COULD, theoretically, drop a pic each week, with the last one coming on April 1st; two days before WonderCon.
And the fact that Ray Fisher was teasing a Cyborg pic following the release of the Cyborg pic, does give the theory some weight.
We'll just have to see.