I think a desktop version is inevitable. The question in my mind is more whether it will be offered at a fair price point.
I think $3,200 US feels about right... much more than that and I believe it will be a non-starter for many.
I've noticed that the OB-X8, like many Oberheim products before it, is being viewed as more of a luxury than the "necessity status" the Prophet 5/10 became for many musicians. I believe there are two factors at play there: the price tag of course, but also the range of possible sounds. I've seen owners of the OB-X8 describe it as a "one trick pony", and I do sometimes feel that way about my OB-6 when I compare it to the Prophet line. Oberheim is a GREAT sound, but I would compare it (in certain ways) to a saxophone... it's an amazing sounding instrument but you don't necessarily want it producing all sounds in a track or even necessarily have it present on every track. I get the same feeling about he OB-X8.
So, because of this luxury item status and lessened versatility, I think there is a category of buyers willing to pay $5k for not only the sound but for the Oberheim experience. Like many (included myself), they've always wanted an OBX/Xa but couldn't justify many prices, but unlike myself, also care about the full Oberheim exprerience including the paddles and large keyboard profile. Then there are those like me who already have an OB6, who do want the sound of the OB-X8, but don't have room for another huge keyboard, and are simply not going to pay $3.5-$4k or whatever for a desktop unit that requires some level of menu diving to access all the features.
While crossing my fingers the asking price comes in at a reasonable level, I'm also looking forward to seeing what Sequential has cooking, and I must admit that the UDO Super 6 desktop does, at times, keep tugging at my wallet.