EA never really kept up the PC version for some reason. I actually used it until around 2001 for all my web artwork (along with a DOS file conversion tool whose name escapes me). I have a friend who's a very oldschool pixel-artist. He still has an old DOS system purely because he's got so much work in dpaint and can't get it running on anything else.

There is a spritual successor of sorts, called Cosmigo Pro Motion. I haven't tried it yet (although I picked up a copy in a Humble dev bundle a while ago). I hear it's the closest thing to dpaint for a pixel-oriented workflow, but with more modern Photoshop-like features, as well as dpaint features from the later Amiga versions that never made it to PC.

It was published by Electronic Arts, who are doing quite well :)