In effect, that is correct. For airlines that offer it, a business or first class ticket could be had for, just as an example, the $398 cost of a coach ticket and the use of a certain number of miles or certificate(s) that takes the coach seat and upgrades it to business or first class, provided the upgraded space is available. In case the upgrade does not "clear", the passenger keeps the coach seat and the miles or certificates for the upgrade are returned or not used.