We can't say for sure who will be in heaven or in hell. We do know, however, that willingly and knowingly rejecting the teachings (some or all) of the Church constitutes heresy, which is grave matter, and can most certainly be a mortal sin. If an individual persists in this, and then receives Holy Communion in a state of mortal sin (which then constitutes another mortal sin), that individual will go to hell.
It is not up to us, however, to judge the heart, but rather to pray that all who claim the name "Catholic" will live in accord with all that Holy Mother Church teaches.
I, personally, think that all cradle Catholics need to make the same profession of faith at some point that converts do:
"I believe and profess all that the Holy Catholic Church believes, teaches, and proclaims to be revealed by God."
Notice how it said "all". Not "some," or "those things which I like," but ALL.
Being a Catholic is a serious matter, and one mustn't take the protestant attitude of "picking and choosing" which beliefs are convenient to one's disposition in life.
This means that in order to be a faithful Catholic, one must (for example) reject all forms of abortion and artificial contraception as gravely evil; one must view homosexual acts as intrinsically disordered; one must accept that the Holy Catholic Church is the final and ultimate repository of God's revelation, and all salvific truth and grace is contained only in her; that the Pope is the vicar of Christ on earth; etc.