1) Flying Nazguls, first and most obvious - and Sauron would know they are coming, being unoccupied with war with Gondor.
2) By skipping Rohan and successively Gondor, Aragorn never becomes a king, kingdom of humans still most likely falls.
3) Nobody solves the Saruman threat, so in the meantime he becomes more and more powerful - probably crafts his own ring or in any case gets so much power he is unstoppable, even if The One Ring is destroyed. Films don't mention this, but in the book he escaped Orthank(and wasn't shot by Legolas like in the film) and took over Shire which he ruled for quite a while - he still had lots of magical power,even after destruction of the Ring. Remember that he was like demigod.
4) Boromir never dies, so he would probably succumb to the power of the ring eventually and took it from Frodo if this plan was not implemented very very quickly, which is unlikely.
I might be misremembering, but I'm pretty sure that Legolas did not return to the Shire with the hobbits. According to Wikipedia, he was shot by "Hobbit archers" from the impromptu militia the four adventurers organized.
You are indeed correct. If memory serves, the actor (Christopher Lee) was upset, even lawsuit upset, about the cut from the theatrical version as its removal reduced his points on compensation.
1) Flying Nazguls, first and most obvious - and Sauron would know they are coming, being unoccupied with war with Gondor.
2) By skipping Rohan and successively Gondor, Aragorn never becomes a king, kingdom of humans still most likely falls.
3) Nobody solves the Saruman threat, so in the meantime he becomes more and more powerful - probably crafts his own ring or in any case gets so much power he is unstoppable, even if The One Ring is destroyed. Films don't mention this, but in the book he escaped Orthank(and wasn't shot by Legolas like in the film) and took over Shire which he ruled for quite a while - he still had lots of magical power,even after destruction of the Ring. Remember that he was like demigod.
4) Boromir never dies, so he would probably succumb to the power of the ring eventually and took it from Frodo if this plan was not implemented very very quickly, which is unlikely.
In any case, it shows how brilliant Tolkien was.