I'd say it's certainly possible. The problem is that over the last 4 years we've learnt to wait a bit longer before calling short periods of excellent play like they're the symbol of great things to come.
Rozier right now is better offensively by Marcus by a mile. His shooting is excellent and he's making better decisions. He has the potential to be an offensive All Star caliber player in the NBA. The great scoring combo guards are those that can:
1) score in transition
2) shoot the 3 from 33%+ and be a perimeter and interior threat
3) take players off the dribble
4) seek out and finish through contact regularly
5) will find the open team mate if they have a better shot
Terry is doing all of the above so far this (short) season so far.
His biggest problem right now is that we are a good team and he isn't getting enough time to dominate games offensively, whereas Marcus has had/seized that opportunity and shown his defensiveness dominance to a level which will be hard for Terry to ever match.
Terry wants to score on every possession and it's bursting out of him with his confidence, I also think that this is effecting his decision making and making him force the issue too much, leading to near turnovers and turnovers.
But yeah, if Terry keeps playing this way for the rest of the season, I'd argue he might overtake Marcus- especially if Marcus' offense doesn't improve at least % wise. Terry is like Monta Ellis with a better handle and better defense, he just hasn't shown the consistency that someone like Ellis has shown for a whole season.
The good news is that if this does happen, and he turns out better than Smart, then we'll have a All NBA first team defender in Smart and an All Star scoring guard in Rozier.