Only 21 were made. One crashed. One is in a non-flyable condition sitting in the Wright-Patterson Air Force Museum.
Only 19 are flying. The article is wrong.
How much longer will they be in service? Is there a new gen planned?
Actually, the article is correct. 21 "flyable" Air Vehicles were built. Either 2 or 3 additional fuselages were built (I don't recall the actual number,) and the one in the Museum at Wright-Patterson is one of those. Another was used in the "bend" test, to see how much loading the fuselage would sustain.
I was stationed at Whiteman AFB from 1993 to 1995, working in aircraft maintenance, and was given the chance to go to Plant 42 to explore the insides of AV-18 (Spirit of Louisiana) while it was still being assembled. During my visits to Plant 42, I remember seeing 2 mothballed B-2 bodies, one of which was the original B-2, 82-1066 (AV-1, Spirit of America.)
Also, 20 are flying. 19 are at Whiteman, and the 20th (Spirit of New York) is at Edwards AFB, for testing.