The market is shifting, and for good reason.
It's like in cars. Ordinary people would buy a Honda, but not everyone would buy a Rolls Royce.
.coms are the Rolls Royce of domains. They are more expensive, and you can't really lower the price, it's not sane - as the supply is low. It's diamonds, why would you sell them for ruby price.
Such domains will always be in demand, but for the more upscale customers. Everyday people will buy .xyz or whatever because they DO NOT NEED .COM.
But who does NEED .coms?
Well, in most cases companies with enough cash and brand awareness to think globally and go for the best premium domain. Big firms will always aim for .com but they also usually buy out other extensions. Or, at least, someone starting with a budget, thinking that way, and able/willing to pay up.
So there's time for a new strategy, to adapt to these changes. As I'm writing this, I'm also rethinking mine.
Hold on to your best .COMs. Hold on for years if necessary. Since the rate of sales is like 1%, you'll need 100 years to sell'em all (not gonna happen). But make sure you ditch everything else, everything that a brand would not aim for. If the name cannot be turned into a brand, you need to ditch it.
Lighten your portfolio and in this way you can sustain it. Sales will be rare but with a very good margin. Those top of the line domains will sell, eventually. The mid-value-ish ones, too risque.
That's what I see seasoned domainers doing mostly, nowadays. Time to follow suit.