The rate of expansion is speeding up. If it continues to increase, eventually it'll have observable effects at interstellar scales, and even interplanetary scales, and ultimately tear everything apart in the "big rip". Note that I'm omitting a lot of context here, there's a lot of other factors which make the big rip scenario much less likely.

Also, the age of star formation will eventually end. Stars will stop forming somewhere between 1 trillion and 100 trillion years in the future.