All Protestants are heretics insofar as they deny the true Church of Christ and her Magisterium. There is not a doubt in my mind that the vast majority of Protestants will go to Hell because their religion bears no grace whatsoever. After they are baptised and are justified for the very first time, if they commit even 1 mortal sin they lose the state of grace and will go straight to Hell if they die.
The most horrible thing about this is that, as someone else said, Protestants don't care to find the truth because Protestantism suits them. It is much harder to be a Catholic than it is a Protestant, because the Protestant false religion encourages and teaches spiritual lethargy. Most Protestants don't seem to care about whether or not our faith is true. All they want is to say 1 stupid prayer that means virtually nothing to Christ and then they're "saved". They've sprung forth many heresies and historical fables about the Church, indicating that they don't care about the Church.