Yes, it would be another dongle, but it would not only perform as a pure copy protection.
The difference is, that in case your UAD PCI card burns down after guarantee, it is stolen or got some water damage etc., it is of course the users problem and he has to buy another PCI card ( a Solo core currently is ~$299), but the plug ins ( possibly worth also thousands of $) are still in the user account and can be transfered to a new card /plug in group.
The drawback of it of course is, that the entrance barrier is higher for entry level users, who don´t want to spend a few $100 just to be able to get going. But if there´s real functionality in the "dongle", why not (instead of e.g. buying a SSD for $200 or a CPU upgrade).
But apart from that I also cannot understand, why VSL has that kind of hardcore policy regarding the USB stick. I don´t think it is the usual way companies deal with that problem. Most of them that I know are more user friendly in that point - even those which have much much less advanced copy protection, like simple serial numbers etc (Voxengo, D16, Soniccouture, audiorealism etc.etc.).
Regarding the non-physical download scheme you´re right. That might be problematic. On the other hand, if users here ask for the cost of insurance, why not offering the physical box / recall code on demand for the fee of the shipping costs or so. Fedex could then drop you the christmas insurance kit right on your door, a few days after you downloaded the files.
In the end I also don´t know if we are talking about highly unlikely incidents. I would be very interested to know about the typical failure rate of these Elicense USB sticks after say 7 years in the field
Of course stolen keys would still be a problem, but nothing in life is risk free.