From the FAQ:
"Why did you change artists?
CursedMarked and I had some personal issues to work out, and we felt it was for the best if we no longer worked together. This was a decision we came to after talking about it together. He will not be joining the project again at a later time, and our decision is not up for discussion."
And I'm pretty sure DyneWolf doesn't technically own the art CursedMark did or agreed to take it out reasonably quickly with CursedMark, so it probably won't come back especially when it goes up on Steam eventually.