Possible power ups for Sasuke would be
- rinnegan because of Hashi's DNA.
- PS with some armors equipped.
- can easily able to use his PS unlike Madara which needs to be stabilized
I can't see any of Indra's EMS techniques as a power up for him but more like his own EMS techniques advanced.
Indra was shown in PS and hence Sasuke's ultimate weapon is PS.