Looking back on the leaked Amazon Australia listings in April, the four Deluxe toys that were expected for wave 4 have consecutive product numbers, which means that they were at least originally intended to be released together... and Pipes & Slammer have product numbers before Waspinator.
F0681 Hasbro Transformers Generations War for Cybertron: K Deluxe Shadow Panther Action Figur - $35
F0682 Hasbro Transformers Generations War for Cybertron: K Deluxe Pipes Action Figur - $35
F0683 Hasbro Transformers Generations War for Cybertron: K Deluxe Slammer Action Figur - $35
F0684 Hasbro Transformers Generations War for Cybertron: K Deluxe Waspinator Action Figur - $35
I really hope that they have planned a 5th wave and signed up retailers to it, as we are getting into that part of the year that retailers stop ordering the "old season" and start clearing their shelves in time for the new season of stock that comes out in December/January. The first wave of Kingdom stock arrived in the country in October last year, so if there is a 5th wave of Kingdom and we don't get it here by the end of next month, the focus of Hasbro Australia and Retailers here will be on next year's toyline (receiving into the country and preparing to ship to stores).
And Hasbro seems to have dropped "revision waves" some time ago (maybe the planned waves are spaced out enough that retailers are only signing up to each wave and don't order replenishments, as they expect new stock to arrive at fairly regular intervals)... and in the last couple of years when there has been a full wave of just re-released toys, it gets a new wave number (which you see in Cyberverse and Rescue Bots)... when in years past, it would usually be called a revision wave (and we sometimes had revision waves that had a new figure in, which made it even more frustrating to keep track of, or track down in some countries).