So the two main ships that we certainly expect to see from Rebels, would be the Quasar and the Hammerhead. For purposes of gameplay, I'd expect the Hammerheads to obviously be rebel, but the Quasar to be Imperial (Even though it's stolen by rebels in the show). But would wave 6 be only a 2 ship wave?
I doubt we'll see 2 more squadron packs with the next wave, considering that since the Correlian Conflict is likely going to arrive the same day as Wave 5.... Wave 5 will end up being the biggest wave for squadrons since the game launched - so I'd expect Wave 6 to either be 4 ships, or the two mentioned above plus maybe 2 more flotillas.
If it's flotillas, the door is open for larger sized flotillas - such as a CR-90 flotilla on a medium base, or something to that effect - Perhaps even a mixed ship flotilla on a large base - A Nebulon + 2 CR-90s, or a Gladiator, Raider, and Gozanti... something wierd like that... but I think that some type of "Battle Group" flotilla might be farther down the line and not in wave 6.
So back to the 4 ship prediction - If indeed I'm right and it's Hammerhad + Quasar... then what would the other two be?
And another question - What commanders are we likely to still see? I don't think we'll see Thrawn until we get a better glimpse of the ships from the 7th fleet, so I think it's more likely we might see some familiar faces like Leia and Lando as commanders, and I think we could also see Sloan for the Imperials since she's been in several books now, - but I also remember that each time we DON'T see Piett, it's more likely that we get an SSD!