The future tense seems vacant and, on others’ lips, jarring.

Verb conjugation has become muddled, as well. Which is correct: “I am a neurosurgeon,” “I was
a neurosurgeon,” or “I had been a neurosurgeon before and will be again”? Graham Greene once said
that life was lived in the first twenty years and the remainder was just reflection. So what tense am I
living in now? Have I proceeded beyond the present tense and into the past perfect? The future tense
seems vacant and, on others’ lips, jarring. A few months ago, I celebrated my fifteenth college reunion
at Stanford and stood out on the quad, drinking a whiskey as a pink sun dipped below the horizon;
when old friends called out parting promises—“We’ll see you at the twenty-fifth!”—it seemed rude to
respond with “Well…probably not.”
what does"The future tense
seems vacant and, on others’ lips, jarring." mean?