Certainly it would be possible for this to happen, depending mostly on the area. Many trenches were built in particularly waterlogged ground so would likely have collapsed quickly after their disuse. Others would have been filmed by inhabitants of the land they were dug on.

The difference in WW2 compared to WW1 is that the static lines of trenches didn't have the same place they did on the western front, many of these areas were passed by relatively quickly, the British and French retreating quickly in the early war and the Germans doing the same in the opposite direction.

None of this is to say that they would not have been used in skirmishes or battles, several older fortifications were used during the war (an example being the Brest Fortress used by the Red Army in 1941 which had been built in the 19th century), trenches just did not hold the same significance they had previously.

Trenches were hugely popular in the Spanish Civil War. However trenches weren't very effective when the other side had planes, accurate and very powerful artillery, tanks etc. (so Germany, France, USA, Russia, but not Franco Spain or the Nationalist Government). Occasionally trenches were used on fronts, but not in the same way as WW1. Soldiers in the British army still learn to dig trenches to this day, they are very useful as a temporary defensive position against over infantry. Bullets don't dig deep into dirt.