Why is everyone sayong "Stop the movie! This will be horrible!" you haven't even seen it yet. The movie hasn't even started to film scenes or record music. Chill. Pass judgement when you see the movie.
The article most likely means Cohen will talk-sing the part, which is fine. The article stated he can sing, his voice is just too low. Why is everyone worrying so much. Sondheim has a say in this and is approving the choices they make. Relax.
Besides, as other people have said, if you don't want to see the movie, then don't see it. If the movie sucks, it's not the end of the world.
I am a firm believer in serendipity- all the random pieces coming together in one wonderful moment, when suddenly you see what their purpose was all along.