Disclaimer:I'm a Hunter
I don't know, maybe it's because I usually just stick to 3v3 sweats these days due to TTK 6v6 pubs being a cancer, but I'm struggling to see how the Sunbreaker is overpowered, yeah it has a powerful super, but it's neutral game is hella average. It has the shitty T-rex Titan melee, average grenades, though Incendiary is decent if you can get a direct hit, no Shoulder charge so it's mobility is limited and more than half of it's passive perks are only useful if it has it's super, it's a very unremarkable class.
Imagine Bungie finally get around to finally giving us that no super PvP mode we've been asking for, every Titan player would be running Striker because Sunbreaker would be utterly useless. This is why Bungie has to be careful with the nerf(yes, there will be a nerf because the outcry is deafening at this point), because just nerfing the super into the ground would render the class unusable in PvP, they may need to add better passive perks to the classes skill tree to balance it out.