KBFW-LP 6 Arlington and KZFW-LP 6 Dallas are the two 87.75's in the metro. KZFW-LP is owned by Hispanic Christian group, so it's not likely to flip from Spanish religious.
Not sure how long the analog channel 6 Dallas will exist. KZFW-LP has a CP to flash-cut to digital (as KZFW-LP 6 Royse City) and LPTV KSEX-LP has a digital CP that will make it KSEX-LD 6. KZFW-LP will be in northeast Dallas County; KSEX-LD at Cedar Hill.
Interestingly, most of the analog channel 6's left on the air in the state are operating as radio stations: KBFW-LP 6, KXIT-LP 6 Amarillo (relaying "La Ley" KJNZ 103.5 Hereford into Amarillo), and alternative KFMP-LP 6 Lubbock.