What would have happened to Jonas and Gabe if the searchers found them?

I believe that both of them would have been released.  The
people would receive the memories that the Giver had given to Jonas, but they would
recover.  The process of finding a new receiver would begin all over again.  If you
recall, to be released is to be killed.

The children are
both receivers so the process would take longer.  One thing that we are aware is that
Jonas and Gabriel have light eyes which may be a quality that the elders will be looking
for when they look to find a new receiver.