You are forgetting its a family owed business and I bet it's more like a project than a traditional company (a knowledgeable entreprenour's showcase to put out something special), maybe they will sell it in small quantities stil as long as supplies last but I think it's very uncertain if we ever see any new product again I feel like or how long they will still keep selling stuff at all. Had it become a huge instant success and very profitable things might have been different, they did have very good start with the older ZO amps but Zo FS did have a very rough start and it was the lack of beta testing phase which would have had to be done a lot more extensive and probably through beta testers around the world before they had gone retail with it.
All things said, I still use my DigiZoid ZO2.1 to be exact, with the M-Audio Q40 the chemistry is PERFECT and the bass response with this combo is like nothing I've ever experienced and I simply cannot enjoy listening to headphones anymore without using ZO so I hope sometimes in the future I'll still be able to replace the battery if it goes totally bust, I do have a spare one too! In fact, I got them all.

The latest ZO FS while sounding a bit more technically refined as in less "in-your-face" and thus more expansive soundstage wise and with a bit more sparkly trable range, the older ZO2.1 that I use is a very different signature and very in-your-face and warm/lush presentation but still with very natural sounding highs to my ears even if the presence or resolution or whatever is not as high, I still connect with the music better with ZO2.1 than ZO FS, I feel ZO FS would pair better with overly "in-your-face" and warm sounding headphones again but it also doesn't have as much punch to the bass as its previous versions, it's still impressive but it just can't deliver the ZOMG-PUNCH to your face bass (and a very impressively detailed and texture one at that) that is highly addicting with EDM style music (I'm a hardstyle enthusiast myself) compared to ZO2.1 / 2.3.
In a way ZO has ruined my headphone hobby as I don't have any reason to try out any expensive headphone amps anymore as even if they sound technically impressive, it's the sound signature of the ZO amp I use that just keeps me so addicted I don't give a **** in how much more detailed or how much more microdetail or precise it may be, the ZO2.1 keeps me dancing uncontrollably when listening to Hardstyle.... there's no Schiit or whatever amp that will achieve the same.