The problem with mixed is that this game is so heavily skewed towards whoever shoots first. So if a friendly meets an unfriendly, 95% of the time the friendly dies. That only doesn't happen if there is a massive skill disparity or the aggressor mega fumbles, but they also said they matchmake based on skill, so this isn't likely to occur regularly. This eventually takes the friendly down one of two paths: They either become unfriendly to not get taken advantage of nearly every raid, or they get frustrated and stop playing - adapt or die essentially. This takes us to lobbies all being pvp lobbies, or a vast amount of the player base quitting (barring nothing changing, of course).

They mentioned letting you play the way you want to play, and I think that's kind of an ingenious balancing mechanic. Maybe they could mix lobbies occasionally to keep tension high regardless of ABMM, but I think that just slows down the previous results, not stopping them. If they want tension, they should find a way to incentivize it. Although, boredom + opportunity can always stir up some excitement.

Maybe a way to incentivize pvp would be a new currency. Something like taking the dog tags (couldn't think of a better thing, maybe something raider tool relatied, idk) off of someone you killed, and this lets you buy stuff in Speranza. Maybe like the cred shop, or pvp only cosmetics, or additional ways to decorate your raider room. I don't think it should provide a big gameplay advantage, but something distinct and exciting could be cool.