It's the closest equivalent to XCOM: EW's base defense, so I assume that that's the one mission most likely to be restartable. No solid evidence, though.
I did end up going chicken and not enabling Ironman for my third campaign. However, I'm turning autosaves off and only manually saving at the geoscape. I'm also only going to reload for team wipes or failing critical missions (
like retaliations). If I do need to restart at all, since I'm only saving at the geoscape, that means the mission maps will be different if I have to re-do. No save-scum allowed in regards to scouting the map.
Just going to sloooowly make things harder on myself, haha. Not like there's a rush. I can see myself playing XCOM 2 for a looong time. I just really like the gameplay loop, and the randomly generated nature keeps things interesting.
XCOM 2 could easily be my Game of the Year already, but I'm hoping to see Dark Souls 3 try and rival that.
I am a huge Dark Souls nerd.