Ok, I’ll bite.
First off, as previously pointed out, Caladan is the oceanic home-world of Paul Atreides, a.k.a. the “Prophet” of Dune, and therefore – in keeping with the naming convention of the S2400 (creative references to the gear they are inspired by which also point toward the capabilities of their subsequent creations) – potentially represents both the “origin” of several concepts which would become standardized in the industry as well as the “legacy” of the PPG Wave, equally well.
Before I move on, it bears repeating that Isla Instruments has also followed a business model initiated by Moog, Arp, Sequential, etc., namely: start with innovative products which extend the functionality of or otherwise replicate that of preexisting musical instruments before fielding original product ideas or improving upon / reinvigorating / repurposing prior entries from competitors as well as your own development history.
Next lets consider some of Dave Smith’s creations, in the context of Isla Instruments core competencies (12 bit sample technology, sequencing, use of and appreciation for vintage machines which feature SSM 2044 filters):
- Model 600,700,800 - third party sequencers for other companies’s synths
- Pro One - monophonic synth designed to be budget-friendly alternative to Model D, ARP 2600, etc., and in the same market segment as the SH-101,
- Prophet 5/10 and subsequent revisions, Prophet 600, Prophet 6. etc. - polyphonic synths, notably those featuring either/both CEM3340 and SSI filter chips, including the first fully-realized example of digital programmable presets in a synthesizer, analogue or otherwise.
- Prophet VS - Vector Synthesis based on Wavetable (if limited) sequencing
- Prophet X - multisampling and wavetable sound generator-based keyboard/workstation with subtractive synthesis architecture.
Now consider the PPG Wave 2.0 and 2.2., which featured the CEM 3320 and SSM 2044 VCFs, respectively. Personally, I think we reached peak-zeitgeist in the wavetable synthesis market a few years ago, but given their small size, suffice to say that Isla has probably been developing this, or more likely just kicking around the idea, for the past 2-4 years. However, the inclusion of wavetables in a product with some sort of melodic/harmonic focused intent seems a natural conclusion, especially in connection to the aforementioned SSM filters.
Finally, looking back at the history of wavetable synthesis, we know that the PPG had a heavy influence upon the Prophet VS, and the designer(s?) of the VS went on to create the Korg Wavestations. Korg’s iteration is not particularly relevant here, other than to demonstrate that the technology has persisted in being developed, and even when one company abandons its interest the thread is picked up by another. What is relevant is the evolution of wavetable synthesis and, particularly in reference to the relationship between the PPG, VS, and the more recent Prophet X, we see a certain synergy has been preserved between digital samples/wavetables and both the CEM and SSM (now SSI) VCFs.
All this has lead me to my own conclusions, which are in general agreement with much of the speculation going on here. In no specific order, I would say we are looking at some kind of workstation that has the following features.
- multi-sampling- and wavetable-based tone generation
- 2-4 part multi-timbral, mono-compatible stereo architecture
- 1-8 or perhaps even 1-16 voices, possibly freely assignable among the available timbres, such as two 4-voice timbers (two timbres, 8 total voices) or extrapolating that out, something like a 1-1-5-8 voice spread across four timbres
- SSI, CEM, or possibly both filter topologies, though if CEMs are available they may either be an add-on or an optional alternative depending on the taste of the customer
- robust MIDI / CV&Gate sequencer based around the S2400 workflow, but customized for melodic and harmonic arrangement and tweaked to match the workflow and ergonomics of the physical user interface design
so basically I’m imagining something like an MPC workstation/arranger but with a focus on sequencing internal, multi-timbral synths as well as external devices instead of being predominantly rhythmic focused. thus the encoders instead of pads, for creating top lines and harmonies (instead of drum patterns) with and old-school analogue sequencer workflow based around freely assigning pitch to individual steps using potentiometers, or encoders as the case may be.
anyway, those are my thoughts for the day. nothing particularly novel, I know, and I appreciate that some of this is kinda nebulous but I wanted to cover all the speculative bases that keep popping up in my mind, which seem related in an intangible manner that is hard to put too fine a point on, let alone explain in words.
ah well, leave it to those of us who have nurtured and developed our creativity to get lateral, despair when we find out we inevitably learn our speculations were totally wrong and all our hopes and dreams are dashed, then get excited all over again once the details of reality are eventually unveiled. 
on a completely unrelated tangent, what if it is actually a multitrack recorder with rotary mixer-style channel interface? a ‘DAWless’, outboard hardware DAW for the ‘DAWless setup’ DAW users. 
