I believe what Paul said:
(Rom 16:20) The God of peace will soon crush Satan under your feet. The grace of our Lord Jesus be with you.
Notice Paul said "soon".
Why would Paul use the word "soon" if the event still hasn't taken place?
The KJV uses the word "shortly".
No matter what version you use, Paul wasn't referring to something that was going to take place at least 2,000 years into the future.
The answer to that is not the events of 70 AD. It is the conception that the whole 2nd coming (DoJ + final judgement) was to take place together in 'immediately after' succession. That is the view Paul had especially, as nothing in Luke (which is transcription of Paul) hints of a delay or prolongation.
So there are two interesting things about their timing of events:
1, the DofJ could have happened anytime after the resurrection in that generation. It eventually did take place toward the end.
2, the final judgement of all nations was thought to be planned for immediately after that, but was allowed to be later. The allowance is in the following:
*there are 4 options to the 'return of the master' in Mk 13
*'only the Father knows' in Mt24B is about the final judgement
*2 Peter 3