“It will be...that/who...” or “It is...that/who...”?

[diamondcutter]

It will not be you who will have to take the blame for this.

Source：Bobing Advanced English Grammar, World Affairs Press Co. Ltd.

This is a sample sentence from the book above. It’s a cleft sentence. What I want to know is whether “It will not be...” could also be replaced with “It is not...”. If so, when talking about the future, which pattern is more common? “It will be...that/who...” or “It is...that/who...”?

 

[emsr2d2]

It would more naturally be replaced by "It won't be you who'll have to take the blame" (we use contractions in natural spoken and written English much more than textbooks would have you believe). However, it would be equally grammatical and natural to use "It's not" at the start.

 

[Tarheel]

While that is certainly possible, I would be more straightforward. (See below.)

You won't have to take the blame for this.

 

[jutfrank]

I think the speaker here used will in the cleft clause to make it clear that the utterance was a prediction. But if that is the case, it's unnecessary to repeat the future-marking will in the second clause:

It won't be you who has to take the blame for this.