models: Saltarello and Audubon which both were launched after the Marcator (1994 for the Mercator, 1998 for Audubon and 2000-2001 for Saltarello) so maybe the designers at the time did not think it necessary to put a skeleton rotor and surprisingly no other (as far as I know) non skeleton automatic has used the skeleton rotor!
As for comparaison between Saltarello and Mercator but techincally it is more difficult to make a bi retrograde like the Mercator than a single retrograde hand like the Saltarello, furthermore the Mercator dials (even the non enamel) were extremely difficult to make and due to this only about 50 Mercators were made each year.
As for a future use of skeleton rotors? I have no idea but from what I've seen nothing in the short term...
Alex...thanks for the insightful information. Look like engraving on rotor was not really a fashionable signature yet when Mercator was created, however, they managed to engrave "Geradus Mercator" on the rotor rim :) In sum, both Seltarello and Mercator are great peices with great merits. Being able to snap both would be a good dream comes true.
In my case, I'd snap the Saltarello first and linger for while before pursuing the Mercator possibly in white metal.
Picture speaks 1000 words................................
So try to provide 1000 words i mean pics with ur suggestions n queries
my article on Skeletonizing on top of the page :-)