I don't believe that's fair advice.
It is not a dying art form, it's a changing art form. If you don't change, of course you're going to get left behind. Sales consultants today are more or less product specialists; and a LOT LESS hardcore/pushy salesmen.
Either your family does a shit job running a store, or you're blind to all the benefits that come from the business, OR you just don't care. Any of those options, or even a combination are fine, and that's your prerogative.
35 years of being in the store, you'd think if we ran it awfully, then it wouldn't be 35 years long.
Dealership culture and atmospheres are toxic. Unless the store is highly corporate and has proper safeguards in place, the average dealership will be full of golf playing divorcee's that talk about cheating on their wives. It's a very common theme at ANY dealership.
The automotive industry is difficult to exit once your in it. And I am a firm believer that the dealership model will change, just as you say it's changing, but in a way that it moves towards a carmax or Tesla model. It's going to become more and more convoluted as they cut back on sales staff, utilize more electronic devices and porters, and make the sales process more objective.
Point is, salesmen are very disposable. It's not a job that you have much security in and I find it to be not worth it.