While working on a project, I noticed something while driving through a number of DuPage County communities: there are teardown homes everywhere. They are not just limited to desirable downtowns; they are spread throughout numerous residential neighborhoods. They are often easy to spot: much larger than adjacent homes and with a particular architectural style with stone or fake stone bases, lots of roof peaks, and plentiful garage space. Some could be categorized as teardown McMansions. (Some of these homes might be infill homes where homes were constructed on empty land.)

These teardowns follow some of the patterns I found in over 300 teardowns in Naperville. The architecture and design is similar. The homes are often located next to older homes, often from the postwar era, from the twentieth century.
One difference is that these teardowns are spread throughout communities. In Naperville, teardowns tended to cluster near the desirable downtown area. In some of the communities I drove through, teardowns and/or infill homes are all over the place. Some of these communities do not have downtowns like Naperville and have housing stocks of different ages. It was not unusual to see a teardown suddenly in a neighborhood on the edge of a community when in Naperville the teardowns tend to cluster in particular neighborhoods.
In a county that is largely built out and with suburbs now 50-170+ years old, there will be more opportunities for property owners, builders, and developers to tear down old homes and construct new ones. My sense is that while communities may have regulations about what can be rebuilt, the general atmosphere is in favor of these new homes as long as there is interest and resources to make it happen.