There some reasons why, in my personal opinon, new or updated pirate sets will appear:
1) Next year it will be 7 years the 3940 (US 3286) Flagship, 3938 Lagoon, etc... were released, so an update would be welcome and in the Geobra-style to do.
2) The new mould of trousers is very typical for pirates and is probably not only intended for use in this new Pirate-special 4654 and for one klicky in a Roman set.
3) The Add-on sets for replacement masts 7594 and sails 7614 will no longer be available in the DS-catalogue (in Europe) next year.
4) The new Pirate-Micro-set contains a small version of the Flagship but with white sails and with skulls on them, and a new kind of lagoon with a rock-fortress. These don't exist yet (or in that form), while all the other Micro-sets show miniature copies of existing sets. (Fairytale Castle & coach, Noah's Ark, the King's Castle)
5) What will be available in the US (and Canada?) through Target-stores this year: and update of Blackbeard's ship with... white sails with a skull on one of them.
So...
Btw, here a piccie of the Roman soldier with the pirate-style trousers: