Re: not a silly question
A number of people have theorized exactly that.
A lot of work has been done trying to "measure" the rate at which the universe is expanding. The big question: is the expansion rate fast enough to go on forever, creating a sparser and sparser universe spread over infinity? Or is it insufficient to overcome mutual gravitational pull and the universe will eventually slow, stop, and collapse back together?
This field has been changing so rapidly with new research that I actually don't know the current status of this question.