Is it really killed? It is still produced but even more important it has evolved through CityPop to FutureFunk and even has touched a bit other genres. I you haven't yet, give it a try. There are many online radio stations that play both FutureFunk and Vaporwave.

As for the SynthWave (2.0 because the original SynthWave happened in very early 80s and I do not know why it is called that way since it is unrelated and I prfere to call it RetroWave) it is still produced. I suggest you try it, the more recent incarnations even have vocals which resemble a lot the US Pop Rock music of the mid 80s but in some songs you can even hear clearly the influence of ItaloDisco.

I really like both and they are very original and important parts of music history. Still carry in them the seeds of the very early 80s evolution in music aka "New Wave" but have completely different aesthetics (VaporWave is mid 90s nostalgia oriented).

If you search in discogs you can even find collections that fuse VaporWave/SynthWave/ItaloDisco and Funk to produce very ethereal music.

PS there also exists the very difference subgenre of SovietWave