Hi,
In addition to the above I've also had a though about something that might be a bit non-traditional but might also be interesting, though I'm not sure that it would bet fully practical. In general it would be a "kitbashers" kit for ships.
Specifically, I know that Skywave - I think - markets small boxes with sprues containing Modern US, Modern Russian, and WWII era US and Japanese weapins, sensors and helos/aircraft or ship's boats.
And, over the years I've seen a couple articles on how you can convert some old Airfix ships into similar but different vessels (like using a HMS AJAX kit as the basis for an ARETHUSA class ship or converting the HMS BELFAST to a City, Colony or Swiftsure class ship.
In addition, I've also seen where Revell of Germany had manufactured their models of the SMS DRESDEN and EMDEN with alternate parts so that the same basic hull could be used for either the twin screw DRESDEN or the quad screw EMDEN. And finally I also have a small 1/700 model of LCS-1 (from Cyberhobby - I think) where you can see that the manufacturer built the molds to allow for fitting a different stern piece to reflect changes to the later LCS-3 and LCS-5 variants.
So, I was thinking, what if a manufacturer made a couple "base hull" kits that contained optional parts for bows and sterns, etc plus the ability to trim the mid piece to different lengths, so that you could kind of kitbash up your own "what ifs", "never weres", or even build something perhaps not "exactly correct but relatively close to a ship that a specific kit doesn't yet exist for.
In general you could maybe have one kit reflecting US WWII type destroyers, another representing US WWII cruisers, and others representing similar stuff for either the IJN, RN or Germany etc. as well as similar kits for more modern vessels all to a scale where you could add the weapons and sensors and stuff from the Skywave boxes.
In some ways an RN Light Cruiser base model kit might be similar to an Airfix kit of the 555ft long HMS AJAX kit, without its weapons and sensors with the deck and hull either broken into pieces, or at leaset "scored" to show where to cut, to lengthen, shorten and or otherwise make changes to the hull to reflect a 506ft long HMS ARETHUSA class hull, a 485ft HMS DIDO, or a larger City class etc.
I guess in some ways they could be viewed as a "starter kit" for people who might want to try and scratchbuild something, but may want help with the hullform, etc.
Pat