Add a new field to the database called mdl_course.coursedisplay to store the teacher's preference.

Add a new setting named "Course display format" to the course setting page for this field with two settings:
#Show all sections on one page - exactly as things are currently, and will be the default setting
#Show one section per page - will abbreviate the course page to a list of links to individual sections

Note that it's up to the course format to interpret this setting. Course formats can use the setting or completely ignore it if they want.