I guess the lineup wouldn't be that much different from the previous seasons.
I think it's probably all about filling the reserves slot.
For the opposite: Atanasijevic and Luburic both have a great season in Italy and Russia respectively. I think Grbic will start Luburic because he have better defense just like last year and use Atanasijevic when Luburic is struggling in attack. It's a sound strategy but Atanasijevic could lose rhythm but I tend to find Serbia performing better as a team with Luburic. If Atanasijevic could be better on defense then he's the holder. One thing to note is Atanasijevic's improvement with his serve. If Luburic doesn't improve on his serve which he struggled to fix in Russia then Atanasijevic is probably the starter.
Krsmanovic also had a great season in Gazprom Ugra Surgut. I think that will relegate Stankovic to the 4th MB or even be replaced by someone new.
I think Serbia is in dire need of a new libero. I am just not sure who as I am not familiar with the league and Serbia's junior division failed to lit up the skies with their performance. I don't think there is enough material to really have an idea for the future of this position.