If the over-engineering is in the wrong dimension (one that the project doesn't need), then the cost will be double: adding the over-engineering and then detangling from it.
The problem is there are too many dimensions a given project can be over-engineered if the future is uncertain. So even an educated guess has a good chance of being wrong.
The problem is there are too many dimensions a given project can be over-engineered if the future is uncertain. So even an educated guess has a good chance of being wrong.