It could be that, or sarcoptic, or something else entirely. A simple, inexpensive skin scraping will tell.

Oh if it is demodectic mange it may clear utself up or it may not. It may take months before it gets better. And it will most likely return at least once a year or so.

Every dog has those mites living in their skin (as a matter of fact they in every or most humans eyebrows too). Just some dogs have a reaction to them. Which in turn makes them bald.

Some say it is hereditary, some don't believe that is true. I believe it is semi-hereditary.

Not too much can be done to prevent it.
There is documentation that interceptor, if given EVERY DAY can help control it.
Because of the costs of interceptor, most people only opt for that route if it is a small dog or if it gets severe.

good luck