A hard-drive based music server just makes so much sense, it has to be part of the future of music listening. It reduces the noise and errors inherent in jitter, real-time error-correction of a spinning platter (yeah, HD's spin, but only for buffer caching), power supply noise (assuming a music server has a decent outboard ps) and the subsequent rfi and EMI. It provides a better dashboard to pick and choose music selections, and can be pound for pound, cheaper than its high-end transport counterpart.
The downside, currently, is the manual effort required (ripping, lossless compression, manual storage) to get to the starting line. Freeware like EAC, FLAC, Foobar and the like have made this process a little easier, but it's still in the world of pc-nerdizm. Once VRS-like servers are delivered at a value-price, it will take off. Unfortunately, building a business case to be the next VRS is a tough one; computer storage, speed and software change substantially every 6 months, and unless you have a supply chain setup like Dell's, you will wallow in inefficiency and low profits. These are my opinions only, but I think either the Big Guys will produce a good music server, or it will remain the domain of the hobbyist for some time.