We had no indication of what toys would be repacked, until now. Entertainment Earth has a listing for Optimal Optimus offered alone but only coming out October 2018, which is the same release date for the wave 4 deluxe wave. Since this website only sells items solo when they are packaged in solid cases, it would mean that the wave 4 leader case content is just Optimal Optimus packed twice. This is good news for anyone who has been having a hard time finding POTP Leader Optimal Optimus, as you will be getting another chance to get him at retail.
The only glut I've seen with Power of the Primes has been Skullgrin/Dauros with the Liege Maximo Prime Master., and Skrapnel for a while (but even he's managed to shift more than Maximo), with the shelves and pegs picked nearly or entirely clean of every other POTP product in every size class - aside from the Studio Series, the Transformers sections were looking like ghost towns for a while! And now that the Wave 2 restock has finally hit, it seems to be selling at a decent rate.