Question

What is virtuosic? Are there any virtuosic performers today?

Answer 1

I have no idea

Answer 2

The concept of a virtuoso revolves around the idea of extraordinary technique. A virtuoso isn't just a superior musician, but a superior technician.
Perhaps the most important facet of this is that a given skill in singing tends to be inversely proportional to a corresponding skill: singers with great high notes tend to lack low notes, singers with great legato tend to lack coloratura, etc. It's very difficult, as a result, to call any singer a virtuoso unless they possess all of these skills in phenomenal ways.