Keep in mind that polarization is a process that has been increasing over the course of decades. I do believe this is a structural problem, and so I'm trying to resolve it by changing the structure. It's ok if it takes decades, as long as things do change.
Opinions are most entrenched when you have had a lot of time to reinforce them (confirmation bias), and have associated your actual identity with them. However, for those non-core discussions, especially at first contact, people tend to be more flexible (look at Donald Trump, and the way he's been flip-flopping whenever he holds a public round table — I'm pretty sure it's because that's actually the first time he's come into contact with real arguments ;) ).
So, even if we consider those old, core debates "lost causes" for the more entrenched people, our youth will have a different experience going forward, since more debates are new to them than old. If this works, people will get more used to having their opinion swayed, and, God help us, the common culture around debate and discussion will shift.