Yesterday, Yoshinori Ono (one of the big creators inside Capcom) tweeted about the development of Deep Down in Playstation 4.
In the japanese part of the tweet we can read this text (google translation):
Deep down and steadily (provisional), ongoing development! PS4 version of solo play has been able to. The ~ I wonder if I can soon show off in front …
As you can see, Ono only refers to the Playstation 4 version in his tweet. If we remember, the unveiling of this game was, precisely, in the Playstation 4 presentation event.
Here you can clearly see the Playstation 4 controller in the picture uploaded by Ono:
We will have to wait until the official announcement to see if the game will be exclusive or multiplatform.