so you just put it in the future?
Not quite.
I check the prophecies and identify the timeline for when they are supposed to happen.
If the timeline does not fit with history, I check to see if there are any conditions that would have caused the timeline for a particular prophecy to shift.
In the case of the two witnesses, it is clear that they are actual people, not empires (empires are called beasts in prophecy).
The two witnesses prophecy outside of the temple in Jerusalem (Revelation 11).
In order for this prophecy to be fulfilled, it either happened before the temple was destroyed in 70 CE or will happen after another temple is built in Jerusalem.
The writings of Josephus describe what happened in 70 CE, but make no mention of the two witnesses, so there is no verifiable historical fulfillment of this prophecy.
Therefore, the two witnesses will be seen sometime in the future after a temple is built in Jerusalem.