The phrase "a completely different future" is correct and usable in written English.
You can use it when discussing possibilities or scenarios that are significantly distinct from the current situation or expectations.
Example: "If we continue on this path, we may end up with a completely different future than we had envisioned."
Alternatives: "an entirely new future" or "a wholly distinct future".
Greene confided that in contemplating suicide, he was exhausted "by the thought of starting a completely different future" from the one he'd imagined for himself.
Events that we think we have no part in whatsoever can actually affect our family tree, and if your great-grandfather would have ever met your great grandmother, and if he hadn't, then he has different children, and they are part of a completely different future from what had existed before.
"Everybody wanted to live without the czar, but they had a completely different idea about the future," he said.
The Conservatives have now decided to take a completely different stance for the future and they are perfectly entitled to do so.
Infectious (especially virus induced) cardiomyopathy might become accessible to a completely different treatment in the future.
(A completely different way to prevent the future shortfall in Social Security funding -- a way that is seldom discussed in budget negotiations -- would be to lift the cap on wages subject to Social Security taxes. Currently, only the first $113,700 of an individual's annual income is taxed).
The immediate crisis is his main concern, but de Lange's goal is to ensure the zoos have a larger stockpile of goods, as well as funds put away, in the event that the crisis worsens or war strikes, or if a completely different problem arises in the future.
Ultimately, this all falls into the hands of CIOs to manage, maintain and facilitate, and the first glimpse into the future shows a completely different set of priorities.
Instead we agreed to do a future closing at a completely different valuation if we achieve certain business milestones.
A completely different tour".
