Generations is a tough line to push onto retailers, here and in other countries, as it doesn't have a movie or cartoon series (on TV) to "advertise" it for the benefit of retailers, who don't spend their own money to move someone else's brand.
Also, there is no "launch date" to send all the stock out to retailers for them to put on shelf at the same time... it is just more "Transformers Branded" products to order in next time the store or retail chain has the space for it (by selling enough of existing Transformers toys to buy up the new stuff).
The Hasbro warehouse in Sydney probably got all the first (and obviously some second) wave product at the same time from China, but are now just waiting for retailers and franchise stores (like Toyworld and Toymate) to want it.
Toyfair in March would have had Hasbro pre-sell a fair bit of the Titans Return toys to Retailers, but the Retailers are probably not requesting delivery of that pre-ordered stock until they have cleared out their old (Generations) product first.
Next year will be completely different with the Movie toyline, as there will be a release date, and Retailers will be competing with each other to have all of the first waves in store first or on the embargo date if there is one.
(but Generations will still be the secondary toyline that Retailers will only order next year if they have enough space around the Movie toys, and enough demand for the entire Brand by regular customers... IF the Movie toyline isn't too big to shelfwarm with hundreds of trashy gimmick toys again

)