Well lets look at it like this..., Take the former MZ-2000 and up the poly (which casio currently has the ability to do), add some new sampled sounds (which clearly they have the technology to due), add a USB port (they've already added them to the WK's and other models), and freshen up the styles (the MZ already has 4 variations ect).

It really wouldn't be hard. Just look at the general specs for the MZ-2000

Specifications
61 full size keys with touch response (initial/after).
64 note polyphony
16 channel multi timbre
MIDI
562 tones (487 normal tones, 20 drawbar tones, 15 drum sets, 40 user programs).
Layer/split
Auto-accompaniments (start/stop, intro1/2, fill in back, normal, next, break, variation 1/2/3/4, syncro start, syncro stop, rit., fade in/out, ending1/2)
130 rhythms (120 preset, 10 use programmable)
Pattern sequencer: 8 part (drum, percussion, bass, chord 1to 5) x10 patterns, up to 22.000 notes,
real time record,
step record
Registration memory (8 sets x 8 banks)
One touch presets (480 factory presets, 10 user programmable)
Arpeggiator
Auto harmonise (12 types)
Mixer function : 14 channels, external : 16 channels, mic/line : 1 channel)
Song sequencer : 17 tracks x10 songs, up to 40,000 notes, real time recording, step recording, punch in capabilities
Pitch bend wheel Modulation wheel Assignable switch
Size (WxDxH) 1150x425x202 mm
Weight 12.4 kg
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If the MZ had a USB port, more updated sounds and styles along with a bump in poly it without a doubt will be a contender. Those few things aren't beyond Casio's abilities.