Just a little background:
I've been teaching this progression to my private clients for twenty years. In a one-on-one lesson we have success in a day, assuming average-to-good balance skills. The main issue for most of these skiers is that, while they have reasonably modern equipment and can feel that the stuff is easier to ski on, they've never systematically addressed the ingrained habits of up-unweighting and early outside-leg steering. As they age, they no longer have the strength for inefficient skiing all day long. So they ski short days and ski less frequently. They avoid off-piste skiing and bumps. That's not a recipe for skiing into your '70s and '80s.
Regarding the potential market: An NSAA demographic study in 2014 found (if you read between the lines) that while young skiers (under 25) outnumber senior skiers (55 and older) three-to-one, the seniors ski just about the same number of skier days -- that is, the average senior skis three times as many days as the average youngster. That's because the seniors have money, maybe a second home, and most important, free time. As baby boomers age, this trend is accelerating. So the meat of the market is, increasingly, older skiers. The opportunity: extend grandpa and grandma's skiing careers so that they enable the grandkids to learn. The trick: bring them back to ski school and teach them how to ski a dozen runs a day (instead of three) and 30 days a year (instead of 10).
BTW the older-skier target market appears to be working well for niche products like Apex boots, Bogner skiwear and some of the European boutique ski brands. A lot of these folks believe that you get what you pay for -- and that attitude is reflected in the cars they drive and the restaurants they frequent. By comparison to some of those purchase choices, a three-day ski school clinic is a bargain.
Regarding learning to ski on 204s: No clinic needed. Go out and try it, but make sure the bindings are safe and the tuning brought up to snuff. Give yourself a wide-open groomed trail. You'll need a huge stretch of clear space to complete a carved turn -- to get a shorter radius you'll either double-pump or slip the tails. Or -- grab a pair of modern narrow bump skis and head for the bowls. It's an education.