I feel like that's pretty impressive for a show that ended almost 30 years ago. Even the later Deep Space 9 has lost at least 1 by this point, René Auberjonois. And granted it aired 20 years earlier, but all but 3 of the Original Series mains have passed away.

Here's all of their current age status, oldest to youngest:

Patrick Stewart: 82

Brent Spiner/Gates McFadden: 73

Jonathon Frakes: 70

Michael Dorn: 69

Marina Sirtis: 67

LeVar Burton: 65

Wil Wheaton: 50

Even the "baby" of the cast is a half-century old now :chomsky-yes-honey: