Board Thread:Spoilers!/@comment-3010035-20150701044944/@comment-3010035-20150721065302

http://tvline.com/2015/07/20/westworld-ben-barnes-replacing-eion-bailey/

Here it says that Eion Bailey (who plays August) was unable to join a new show due to previous commitments and filiming clashes.

I checked his wikipedia page, and it really doesn't look like he's been in anything significant except Once Upon a Time in the past few years, so I think there's a high possibility of him returning for Season Five!