In its Entirety

So, there are still people alive who have never even heard of Jesus.

Jesus went into Hades and unbound people who did not know him. The common perception of this is that it was everyone who had died to date when he died.

Basically he made himself known to those who did not know him.

The thing is, there were plenty of people that came after he died in that same boat, and still plenty in that boat today. I believe the misconception here is that Hades follows the same timeline as Earth, whereas I see no reason for that to be true, given that we already know God is unbound by time, and so there is at least evidence of differing timelines.

So picture a graph of all people, from the beginning of time to the end, who died without ever hearing of Jesus, they would all have gone into this afterlife, possibly even entering Hades all in the same moment from our perspective, and then Jesus shows up, explains his message, and people accept and are released.

Now, the next logical step is "what about someone who has seen a random Bible verse about, or said by, Jesus on a billboard once in their life. Do they know Jesus?" Seems pretty clear that they don't. In fact, until the entirety of his argument is heard, one cannot accept said argument, in my opinion.

So now I'm picturing all those people going to Hades as well, and Jesus popping in, explaining himself, and saving them too.  (From a graphical perspective these could be different colors then those who had never heard, each hued differently based on their overall exposure and understanding of Jesus' message).

Now hearing a message is not the same as understanding it (reference: the parable of the sower). How many people actually understand the entirety of what Jesus said? Is it required to understand one's own position completely to accept salvation from said position? If so, which seems reasonable to me, Jesus would then go explain it to all of them as well. 

In the prodigal son we see that forgiveness is available, despite previous actions. We also see that this concept is hard for humans to accept. It ends up being the loyal son separating himself from his father in the end, not the father separating himself from anyone.

In the end (Referencing Revelation), there will still be those outside the city, but only because they have heard, understood, and refused to accept Jesus' message of grace in its entirety. The gates remain open as well. This is the God and savior we find ourselves with in the realm that we are in: wise, patient, loving, and inexhaustible.

"I have not lost one of those you gave me." John 18:9.

"Moreover, the Father judges no one, but has entrusted all judgment to the Son" John 5:22