How can you say that? The hard fork can't happen if Bitcoin Unlimited doesn't get at least 75% of the total hash power.
Yes, it can, because the BU developers are not very good at what they do. They have already caused a split once by making a broken block that was only valid with their client. If they had more than 50% of the hash power then the Core chain might never have caught up with it and the split would have been permanent.