There is a Hadith which says that the Satan try to listen to the news which the angels trickle down from Allah from the highest heaven to the lowest. When a Satan tries to snatch it, then a shooting star is thrown at them. When a soothsayer says something from what they try to hear from the Satan, then those Satan say what they heard, but they mix with it many lies as well. So no one even knows the truth at that point.
Fact is, even if someone were to claim they know what the future is and that they received some form of revelation, though they are unbelievers, they are receiving Satanic revelations. These Satanic revelations are all false, and they are given to the liars, not the truthful people. So these astrologers and whatnot are not telling the truth about anything. Everything they say is a lie. This is why we do not believe in palm readings or astrologers, etc., because as Muslims we are not supposed to listen to and believe in lies. It is bad for the soul.
As for what will happen in the future, Allah knows best. We cannot say that everything is written in stone. I can't remember which Hadith said this, but it is certainly a fact that the Divine Decree can in some cases be averted. The Holy Prophet (saw) said on one occasion that prayers avert the Divine Decree. Some things cannot be changed, but there are some things here and there which can be.
Furthermore, if you recall the case of Hazrat Yunus (as) and his people, he told his people by revelation from Allah that they should wait for three days in their homes for the punishment of Allah. When his people heard this, they became very remorseful and they all repented to Allah. And how they did! The Divine punishment was averted and they were not punished. Instead, they became followers of Hazrat Yunus (as). In the Holy Qur'an it said that he had a very large following of people.
So, since Divine punishments can be averted, this means that the Divine Decree is not written in stone. This is why the Holy Prophet (saw) told us that even though the Divine Decree is written for us, even still we should act as best we can. This is the advice he told us, not to just sit back and wait for the Divine Decree to come upon us. It does not happen from inaction, but we are directed to take the best possible course of action, which is to be the best we can in the way of Allah.
Holler back if you're not clear on any of this.