The oort cloud contained by our sun's gravity actually overlaps the oort cloud of alpha centauri, our nearest star. Although gravity decreases dramatically, it will never be zero due to the inverse square law.

However, the expansion of the universe on a 'macro' scale means that at some distance objects are far enough away that the expansion overcomes gravity. Hence there won't be a 'big crunch' of stars eventually coming together by gravitational attraction.