How should I use the in-, im-, il-, and ir- prefixes? Consider the following words: impossible; incorrect; impatient; illegal; irregular; The meaning of the prefixes is the same (negation the adverb), but they are still different prefixes
future tense - I will be or Im going to be - English Language . . . I agree that either is appropriate in OP's situation, but I don't know that your distinction between evidence no evidence holds water In the specific example of what children want to be when they grow up, I think the most commonly heard expression is "I'm gonna be an astronaut when I grow up!" (replace astronaut with child's prospective profession of the moment)