The SGS3 is listed with the FCC as SVDO and SVLTE capable. So yes this function will work with data over EVDO or LTE (once launched) because the 1x radio (voice) is separated and independent of the radios using data.
EDIT - If you ever got bored/curious and wanted to check on a future device look at the FCC filing. The documentation will call out SVDO and SVLTE is it's capable or use the device schematics, look at the radios, and see if 1xrtt is a different radio than EVDO or LTE. As long as the radio for the protocol is separate, they can operate at the same time. Hence why wifi data and talk have always worked on CDMA phones, 1xrtt and wifi have always been separate radios