l was hoping that you would never be a backsilder again.
英语中当与事实不符,尚未发生,或者不可能发生的事经常用到虚拟语气
l am afraid it's snowball's chance in hell
后面不是没有主语,而是用it 代替了,snowball's chance in hell 是毫无机会的意思,也就是it 代替的主语是毫无机会的,前文或后文肯定有提到.