A year ago, maybe even 6 months, general consensus was Bruno should be captain. Others said Ronaldo. Neither seem suitable at the moment, Bruno is in dreadful form, Ronaldo has been pushing to move. Things can change quickly.
I don't think the captaincy actually makes all that big a difference. The bigger problem is the lack of suitable candidates. If you have a number of leaders in the squad, then who is wearing the armband doesn't really matter as much as people think. The primary responsibility is trivial stuff like media interviews, sorting out tickets for family members, keeping tabs on fines or whatever. I don't think it makes a big difference on game day, and it doesn't/shouldn't play a part in team selection.