time will tell
Sooner or later something will become known or be revealed, as in I don't know whether or not they'll like the reconstruction; only time will tell. This proverbial phrase dates from the early 1500s.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.