HD-CVI is one of the leading HD over Coax formats along side HDA/AHD - with most cameras and DVRS now offering multi format support. You can mix and match in any configuration, analogue and HD-TVI cameras up to the maximum channel amount. This makes it a perfect upgrade route if you want to upgrade/add to an existing analogue installation.
HD-CVI recorders even allow you to add an IP camera or two from their range (networked separately)