This is an interesting one.
If PIE never existed, people living in the PIE homeland (Caucasian steppe) would probably still developed chariots and conquer Europe, Central Asia and South Asia. So the proto-language that group of chariot riding people speaks will diverge into many languages in these areas.
My best guess is that these people would most likely be speaking a mixed language of Kartvelian, Pontic and Caspian. The effects it would have on the world is that we would most likely be speaking the daughter language of this “Proto-Caucasian” language that develops in British Isles as international language.
And it's not gonna be fun for non-Caucasians, considering many of these languages have super long consonant clusters. Imagine pronouncing “sprtklti” for “I love you". It just sounds weird right?
English language is odd enough phonetically, but Caucasian languages are simply over the top.