FRANKFURT — A lot is happening in the world of central banks.

In Washington, the Federal Reserve has raised interest rates again to brake the sizzling United States economy. And the Bank of England is also in rate-raising mode.

Not so the European Central Bank, which left monetary policy unchanged on Thursday. No one expected Mario Draghi, the bank’s president, to drop any bombshells when he faced reporters after the bank’s final meeting of 2017. But there were lots of questions about what will be coming in the New Year.

It could be a watershed. The central bank’s own economists substantially raised their estimates for eurozone growth, portending an end to the crisis measures that have been in place in the 19-nation common currency area since 2008. That would usher in a new era, with monetary policy returning to normal and the central bank beginning to gently push up interest rates.

Mr. Draghi’s news conference on Thursday revolved around how soon the stimulus measures might end. While he said there has been “a significant improvement in the growth outlook,” he steadfastly avoided any statements that would change investor expectations. Still, Mr. Draghi offered a few clues about the central bank’s evolving views.