Also think so. According to Ben Ang, additional switch-out parts for Optimus Prime (e.g. hologram arm) will be included with Starscream. However, as of now, licensor agreement is still pending. Hence, so far there has been no official announcement. But even without these parts, Optimus Prime...
Thanks. Perspective is indeed playing tricks here. In reality, the size of the Sandtrooper is just fine compared with the Tamashii C-3PO and the SS R2-D2.
I jumped on the waitlist on the 6th of February and received a corresponding conversion mail on the 10th.
It really is an amazing statue :-). Hopefully, yours will convert as well. Good luck.