Well, you cited music performance, but so did the guy who did the research everyone who talks about "10,000 hours" is referencing:

"Even in music there is evidence for improved skill. When Tchaikovsky asked two of the greatest violinists of his day to play his violin concerto, they refused, deeming the score unplayable (Platt, 1966). Today, elite violinists consider this concerto part of the standard repertory. The improvement in music training is so great that according to Roth (1982) the violin virtuoso Paganini "would indeed cut a sorry figure is placed upon the modern concert stage" (p. 23)." [1] There are no stationary targets.

He uses this as evidence that the notion that "a sufficient amount of experience or practice leads to maximal performance appears to be incorrect" [2]

[1] http://projects.ict.usc.edu/itw/gel/EricssonDeliberatePracti... p.366

[2] Ibid.