A computer is still easier by far–if you know your way around EXS24, for example, you can get a device multi-sampled pretty quickly, with velocity levels (I actually still use a fifteen-year-old template for this very thing). And, you can automate the sample generation / processing / etc.
You just cannot do that with an E4, on its own (with its limited sample RAM and velocity layers) as easily; in general, I used computer-based editors such as Peak or Spark to handle sample maintenance in the old days (over SMDI or MIDI SDS, for other stuff).
I'm not as sold on the E-mu rack hardware thing as you are–to me, the Emulator X + PCI card was the beginning of the writing on the wall for that concept, which is why I'd rather see a hybrid that doesn't attempt to do too much with a tiny interface.
And while I agree with you that it'd be nice to run samples through analogue filter ICs in a modern instrument, that's no longer enough to justify the R&D required (witness the discussions on the Quantum regarding the lack of FM, even when the rest of the engine is more-than-well-equipped).
It's gotta be a fully-fledged digital instrument, or, alternately, an analogue add-on to an existing digital processing core, with the understanding that, if it's fairly well engineered, that it may outlive the lifespan of the computer systems used to design it in the first place!
I'd be happy with an iPad-based waveform/model editor, some control knobs, decent multimode filters, and a bunch of analogue outs.