I think the best course of action with the "C" is to leave it vacant until a legitimate captain emerges
I've always maintained that I hate giving young franchise faces the captaincy for marketing purposes, children do not lead adults as the adults don't take them seriously, it puts an undue pressure and strain on someone like Celebrini to become a leader when he really should still be learning how to be a premier player first, let him ruminate and if they REALLY feel he's emerging prematurely just give him an "A"
I also don't like Toffoli as captain, I don't want the guy who happily signed with the worst team in hockey so he could live at home comfortably while he drinks beers with children to be the tone-setter for the lockerroom, just let an actual tent-pole player emerge, there's no reason to rush into a decision
Ironically, the Couture situation gives the team cover for this, "we have a captain, he's working hard toward recovering from injury" allows the team to avoid tacitly admitting that no active player on this roster is fit to wear the "C", we get 2 bonus years where we can let the lockerroom sort itself out
Hell, maybe the next captain isn't even drafted yet, it doesn't have to be someone we've already seen on the team, no one on the current roster has ever lead the Sharks to a remotely passable performance, just let the team grow and a leader will emerge naturally
*DISCLAIMER*
I fully believe Celebrini will one day be captain and will do a good job, just please don't make a 19 or 20 year old wear the "C" just because he's talented and marketable, let the leaders lead and the players play