Low GPA, BCG consultant... What are my chances of getting into a top B school?

I studied Industrial Engineering and ended up having a mediocre GPA (3.0). My school is top in my country and it is not easy getting high grades. However, I recieved and accepted an offer at BCG. If I manage to succeed in BCG and stay there for 4 years, what do you think of my chances of getting into a top MBA program? How will the low GPA, good work experience balance eachother out?

I also have a pretty interesting background, ex-army and im pretty sure Id be able to get a pretty high GMAT (Specially good at quant).

Thanks for any insights!