What happens in the future?
The expansion of the Universe is a key feature of the Big Bang cosmology and is a generic property of the Universe we inhabit.
The future fate of our expanding Universe should depend on how much matter (= mass = gravity) is in the Universe.
There are several possibilities:
(1) Recollapsing Scenario
We can’t tell the scenarios apart at the current time because all of them predict an observation of a (currently) expanding Universe.
We can’t look into the future to see what happens next, so we have to look for clues in the past.
Fortunately, this is easy! Because of the light speed travel time, everything we see around us in the Universe is on a time delay. More distant objects appear to us as they looked longer into the past.