People drive around the country and see all trees everywhere and think that we can't possibly be running out of them.  The problem is that the majority of them are of little value as lumber and when a tree is cut, it takes 50-100 years to grow another similar tree (much longer if the tree happens to be old growth Douglas fir).  Forests also provide recreation, habitat for wildlife, clean water and a place to stash a lot of carbon, so cutting them all down is not only politically difficult, its self defeating.  Changing to steel, or concrete or even straw will have its own set of problems, and undoubtedly people will be arguing about which is better for a long time yet.  As individuals all we can do is make educated guesses and try to use materials wisely.

If we don't harvest sustainably, eventually there will be nothing left to harvest.  This is of course a complex topic, because it involves everything you need to know to farm trees.  It would be a good start if we could get everyone to at least agree that this is necessary.

The first step is to make your house just the right size.  For most people there is no reason to live in a castle, nor is there one to live in tent.  Every room in your house should be necessary, and there ought to be enough room to keep from being on top of each other.  Sure, those big grand entryways impress people, but otherwise they are virtually never used.  On the flip side, we could all live in a few hundred square feet because in many places in the world people do it, but for most of us, doing so would result in terrible unhappiness.

The second step is to try to use fairly durable materials.  Having to replace something every ten, or even twenty years is not only expensive, but results in a lot of material wasted in the landfill.

The third step is try to find the most sustainable materials you can.  If the seller is advertising sustainability, your purchasing an incentive to change along with the product.  Reclaimed materials are an even better bet, and often create an aesthetic that can't be duplicated with new materials, but cleaning them up for reuse can be quite expensive, especially if you've never done it before.  Although knowing if your choices are actually sustainable requires significant research into how they were produced and what will happen to them when you're done with them, the simpler way is to treat them all as if they were expensive and just use your common sense.  There are no absolute rules, only guidelines.  

The final, and maybe most important, is to make is beautiful and functional.  If your house is considered beautiful by many, it is much less likely that the future owner will extensively remodel it.  Likewise, if your house can accommodate a variety of family sizes, it will be left alone.