LEts be realistic,
At the moment they are important because with out the required you cant go to college but when it comes to uni,
They will look at you A levels (some of the big unis, oxford, cambrige, ect look at them but thats just because there are so many people going for places with the same a levels so they look at GCSEs)
Once your at Uni and get your degree your employers will look at that. For example, i want to be a maths teacher so i need a PGCE in maths and to do that i do need a C in english GCSE an A level in maths and a degree where there is more than 50% maths. For what i want to do they will look at all of them.
If you are not planning on going to uni, then employers want you to have a certain amount of GCSEs as well. My couson dropped out of school months before her GCSEs and tried to get a job in sainsburys and couldnt because she didnt have a GCSE at a D in maths or english. So basically you need them but A levels sort of cover them