Already possible with OT. 
Wavetable synthesis
Probably not a good example of granular synth, if you listen some parts I think it’s not so far, considering synths you can make from drums, even if I’m not subtle at all!
With Octatrack you can use 8 instances of a sample, 24 lfos, set start / length points, 250 parameters can be modulated by the crossfader, lfos modulations added, (the crossfader can be also modulated by a midi lfo), plus 8 midi tracks with 24 more lfos, being able to play the 8 audio tracks with an arpeggiator, realtime sequenced sampling.
Etc…
I think OT can be a really interesting granular synth, 8 voices / grains limited.
With external trickery, it can be used in a polyphonic way.