"...how long the note should sustain is simply not available at the moment a mere note-on message is received and at which the algorithm would have to pick an articulation."
Are you suggesting that VSL developers can't break the time-space continuum, i.e., tell the future? :-) I too was going to discuss the impossibilities, but A. I have a lot of faith in VSL to do something outside of my imagination, B. they might aim for a "second pass" algorithm (as Kai described), and C. it was bedtime. But you are correct, of course, that note-on and velocity only, played live, has too little information to pick sample length and playing style.
Bring on the speculation. I haven't seen a tease campaign this much fun since the advent of Vienna Instruments.
By the way, for you folks in the States, you're getting a further discount (over 15%) if you buy in dollars (Ilio, et al) than online (in Euros). That is another kindness VSL extends, often unnoticed. It makes the math a whole lot simpler. Also, if you buy in Euros from the States, your credit card may ding you with a currency conversion fee.
There's a speed bump, though, with Ilio: they can take a day or so to confirm the purchase and send the codes.