Learn English – Is “will be going to” correct

Using will (or shall) is the proper way to form the actual future tense, and is completely generic. IT can be used in any case in which you wish to refer to the future.

Going to + verb is a shortcut construct that is commonly used in many situations. It is typically used to express occurrences in the near-future.

In many cases however, particularly in colloquial speech, the two constructs are virtually interchangeable.

Wikipedia has some additional notes on usage:

Going-to future is used when the speaker wishes to express certainty about the future based on evidence or fact from the present or the speaker's opinion: "If you do not stop, you are going to be caught by the police and hauled back to jail." "Our houses are going to be swept away by the impending storm." While the "will" and "going to" constructions are often interchangeable, only the "going to" construction can denote former future intention (e.g. "I was going to eat dinner, but decided not to").

Question: "Will the cake be burnt?"

Positive answer, short form: "I hope so."

Positive answer, longer form: "I hope it will be burnt."

Negative answer, short form: "I hope not."

Positive answer, longer form: "I hope it will not be burnt."

The longer form can also use the contraction of "will not", "I hope it won't be burnt."

The longer form of the negative answer "I hope the cake isn't burnt." would be appropriate had the question been "Is the cake burnt?".

This is how I think:

"Is" in the questions => "Isn't" in the negative answer.

"Will ... be" in the questions => "Won't be" in negative the answer.