SF and "sawmill"? These are not exactly compatible... I would rename/change your facilities and resources.
I would not. :-) Trees evolved through 100 million years, so it's no wonder, it's one of the best building material regarding cost, strength and other parameters. I'm pretty sure mankind will use it even in the distant future. What's the alternative? Plastic? On terraformed planets, there's no natural oil. Without oil you don't have cheap plastic. Just look at the plastic production chain in Zandagort: lumber -> coal -> oil -> plastic. When the oil reserves are out on Earth, this will our future too.
In hard sci-fi you have to take physical laws and other constraints into consideration. There's no such thing as a "supermaterial" that is cheap and fits all needs. Or if there was, there would be no economy (which is not really good in a strategy game). :-)
