I like to create the sort of set up that is based around one large instrument. Several years ago, I was in the midst of building a mostly-Evolver set up. It was a master plan that would wonderfully serve my musical needs. Then one day, unexpectedly, DSI announced it was retiring the Poly Evolvers. It completely messed up my plans because I had wanted all new instruments that were still in production and fairly maintained. Now my set up is built around the Prophet '08 and I'd still like to add at least one more unit to it. But can I depend on the instrument still being around in a couple of years? Nope. Should I next build my set up around the Prophet 12? But that will eventually pass away too. It's very frustrating to a musician who knows exactly what he wants to do and has no interest in merely following the latest populer synthesizer trend. The "in thing" is the last thing that interests me and is usually the worst thing in my opinion. And yet, the synthesizer is an instrument that is totally at the mercy of trends and markets, so unlike traditional instruments. It's a very a-musical situation that has the potential of pushing away altogether a serious composer/musician.
I will point out, with all due respect, that you're the cause of your own angst here. The pressure to "follow the latest popular synthesizer trend" that you feel is internal, and a byproduct of your requirement that your setup be based around in-production instruments.
To put a somewhat different spin on your comparison of synthesizers to violins: Synthesizers are like violins in that they do not become obsolete. An Evolver will be as musical in 50 years as it is today. But both a violin and an Evolver will require care by the musician, and occasional service from a knowledgeable party (a luthier and a tech, respectively) to last that long.
If a studio of Evolvers suits your musical vision, why would you compromise that vision by jumping on the latest bandwagon? It can't be a maintenance issue; electronic instruments can potentially be maintained for decades after they're discontinued. There's pretty much nothing that can go wrong with a DX7 that can't be fixed still today, and there's pretty much nothing that can go wrong with an Evolver that won't be able to be fixed for the next thirty years.