Exactly. I believe the 60 million infections delta was estimated for April 6th (figure 4), so the counterfactual would be considerably worse as of today.

"So far" meaning "might save more later" or "only postponed, not prevented"?

By now we have learned that masks + distancing is enough to stop this (Drive R0 below 1, it will die out in time.) If we were serious about doing these things the cases--and deaths--would be prevented, not merely postponed.

The latter. That's always what "flattening the curve" has meant. The total area under the curve (i.e. total unique infected individuals) stays about the same.

"Flattening the curve" is not the only possible outcome.

A cure, an inoculation, or segmenting geographic regions until localized herd immunity (like New Zealand just did) are all examples of cutting the curve short.

Vaccines are far away from approval for widespread use, and New Zealand's situation as an island nation is not applicable to something like 98% of the World's population and quite frankly, irrelevant to the discussion.