I don't speak for GMK and have no relationship with them (beyond hoping they can make a number of keycap sets I'm waiting for). I'm disappointed that the sunset novelty is now absent from the kit, but am pleased that the kit will be able to run. I'm writing this comment to correct some miscomprehensions of IP that have been discussed in this thread, and to answer some of the questions I've seen.
In Europe in particular, we have an exciting variety of intellectual property rights that can apply to keycap design. Without performing a detailed analysis I cannot speak with certainty on the matter. However, my suspiscion is that the design of a novelty keycap like the sunset gives rise to a number of relevant rights, including unregistered (at least) design rights and moral rights. These rights exist independent of any copyright or other rights in any artwork that may have inspired the design of the keycap \[0]. Accordingly, although an artwork may be public domain [1] a keycap based on that artwork may still be subject to IP considerations related to the design of that keycap.
My first point is therefore that simply because others are (apparently) free to use the iconography of the sunset image does not necessarily mean that GMK are free to use the existing sunset keycap mold without the approval of all persons who hold IP in the mold.
The practicalities of dualshot ABS molding impose a variety of limitations on what is possible to make as a keycap, in particular relating to line thickness. Given we are talking about a design on a 1U keycap, there is a limited amount of freedom available for a designer to move away from any existing designs. Particularly pertaining to design rights, the legal test for infringement is based on whether "a different overall impression" is conferred upon a viewer of the keycap [2]. Accordingly, even if GMK were to make a somewhat different design that still represents a sunset with repeated horizontal lines there could still be an issue.
My second point is therefore that technical considerations may limit GMK's ability to avoid any rights that exist in previous keycap molds [3].
IP litigation, particularly in Germany, is scary. A manufacturer of a product can very quickly find themselves barred from selling a product or ordered to destroy those stocks they have of it. Imagine if GMK did have such an issue, and the massive reputational damage (not to mention the logistical hurdles) involved in giving refunds to people and/or delivering a set that does not look as promised. The penalties of getting IP wrong are very significant. The legal costs involved in clearing things which are controversial or questionable are also significant, and do not provide any guarantee that things will go your way if you do end up before a judge [5].
My third point is therefore that it should not be surprising if GMK are being very cautious around any IP issues associated with keycap sets.
Overall I'm not surprised with how things have worked out, and am pleased we're back on track for me to have a truly lurid keycap set.
[0] This comes from the principle that each act of creative work can give rise to its own protection. For example, if JK Rowling took an existing piece of Harry Potter fanfiction and published it as her own, this would give rise to a (potentially very lucrative) copyright claim on the part of the fanfiction writer. Even though the fanfiction itself is based on/is an infringement of an existing right, new and separate copyright (and other rights!) still subsist in that work.
[1] I do not believe that the sunset design ("as such") is in the public domain. It seems to be an orphan work in that no-one is taking charge of the right or challenging people using it, but nevertheless if chain of title could be established somebody could claim ownership of it. This would be fun(tm).
[2] In principle the breadth of protection should be limited by any technical considerations that apply (does the design provide a different overall impression to the informed user who would take into considearation the freedom available to the designer. In practice there have been some big cases (such as Procter & Gamble vs Reckitt Benckiser) where injunctions have been granted an significant financial hardships imposed by the court of first instance on what, in my opinion, is a clearly different design.
[3] This is less relevant for "functional" keycap design since fewer rights are attracted to such design. This may explain why someone was (apparently, I'm learning this for the first time today) able to recreate Katakana[4] molds when a previous creator of them was not amenable to the use of the old molds.
[4] Also the shape of Katakanas are firmly in the public domain, unlike the sunset design.
[5] Again, I refer to Procter & Gamble vs Reckitt Benckiser where it took an appeal before the "correct" result was obtained.
