I see no reason why you can't but it is kind of meaningless. Bright future means your future is full of promise. A gloomy future is not something you want or will look forward to with anticipation. Just as bleak is another you don’t want. On the up is good whereas if your future is in the toilet or heading there then you have issues to sort out.

I completely agree with the previous posts, I have never heard it used.

I’ve never heard that before and don’t know what it means. If you’re referring to some grammatical term, I’ve never heard of such a thing either and don’t know its meaning. Is there an „impure future.“

I've not heard this phrase before, but it might exist. Can you provide some context?