I think it's actually possible Bernie could drop out next week, if he gets completely shellacked.
Doubtful when he'll probably win all 4 states in May.
The more I think about it, I don't think KY and WV are in any way comfortable for Sanders. KY is closed (remembering that in OK, Clinton still won Democrats by 9-10%), WV is semi-closed. Indiana is open, so he could absolutely win there and he'll win OR but since it's closed, the margin might be a little underwhelming and the delegate split not all that great.