Quick! Can you name how many player producible ships were added to the game between the Revelations I expansion in Nov 2006 which added the "Tier 2" battlecruisers (Drake, Hurricane, Harbinger, Myrmidon) and the "Tier 3" battleships (Rokh, Hyperion, Abaddon, Maelstrom) and the Incarna expansion in June 2011?
Amarr Magnate - Empyrean Age, June 2008
Orca - Quantum Rise, Nov 2008
EDIT: I was reminded that the four Tech III Strategic Cruisers were added in Apocrypha, March 2009
Noctis - Incursion, Nov 2010
Did I miss any? There have been other ships in that timeframe like the Primus, Zephyr, Apotheosis, but they are all gift ships from CCP that have limited numbers and typically limited utility. And how many have been added since then?
Tornado, Oracle, Talos, Naga - Crucible, Nov 2011
Venture, Dragoon, Algos, Talwar, Corax- Retribution, Dec 2012
Navy Drake, Navy Hurricane, Navy Harbinger, Navy Myrmidon - Odyssey, June 2013
Astero, Stratios - Rubicon, Nov 2013
One of the big lessons CCP took from the Incarna disaster is that players love, LOVE, new usable ships. I didn't include the Gnosis in the above list as it was a limited gift instead of new ship but it was very functional and still sees a lot of use in space. Thus it is no surprise that for the past three years we have seen more and more new ships added to the game, and I expect this trend to continue for the foreseeable future.
But what roles can future new ships fill? Here are some ideas that I think are reasonably likely to be seen in the coming expansions:
Tech I Disruption Battleships - Caldari have the Scorpion, so expect the other factions to get similar disposition ships while the Caldari get a second Combat battleship to compliment the Rokh.
Tech II Frigate Command Ships - Call them Field Command Ships or Squad Command Ships, they are Assault Ships that also fit a single Warfare Link for those fast moving Assault Ship fleets coming in Rubicon I talked about yesterday. (Could also be a Destroyer hull.)
Tech II Frigate Logistics - The Tech I logistics see use but might be just a little too fragile or short ranged, this class will give a bit more pow while still not overshadowing cruiser logistics (either Tech I or Tech II).
Sisters of EVE Battleship - Its only a matter of time.
Navy Rokh, Navy Hyperion, Navy Maelstrom, Navy Abaddon - Hey, there was no real need for the navy battlecruisers either.