One of the reasons why I know the end must be "close" is because people who are able to understand what is happening are dwindling in number. If this world goes on long enough there wouldn't be anyone left alive worth saving.
Sad but true. Psalm 53 comes to mind:
1 The foolish one says in his heart:
“There is no Jehovah.”
Their unrighteous actions are corrupt and detestable;
No one is doing good.
2 But God looks down from heaven on the sons of men
To see whether anyone has insight, whether anyone is seeking Jehovah.
3 They have all turned away;
They are all alike corrupt.
No one is doing good,
Not even one.
4 Do none of the wrongdoers understand?
They devour my people as if they were eating bread.
They do not call on Jehovah.
5 But they will be filled with great terror,
Terror they have never felt before,
For God will scatter the bones of those attacking you.
You will put them to shame, for Jehovah has rejected them.
6 O that Israel’s salvation may come from Zion!
When Jehovah gathers back his captive people,
Let Jacob be joyful, let Israel rejoice.