As I said before, without humans, there'd be a major shift in the environment. Not in a way that it would threaten other species but rather strengthen their life span. Even the domestic animals work revert back to their original biology. There's a possibility of extinction for them but there's also a high probable chance of adopting wilder ways.
There'd be no more deforestation and destruction of habitat to accommodate man. Slowly, manmade structures will disintegrate, earth will be repopulated by fauna and flora in many years to come. No more pollution, the oceans and the atmosphere will be cleansed off and pure again.
Man will no longer be on top of the food chain. Although initially there'd be drastic increase and decrease of some species. Naturally, predator and prey relationship would balance this. Man has always altered the environment so without man, nature would run its full course.