Jamieson, Fausset and Brown on Obadiah 1:17

17. upon ... Zion ... deliverance--both in the literal sense and spiritual sense (Joe 2:32; Is 46:13; 59:20; Ro 11:26). Maurer as the Margin explains it, "there shall be a remnant that shall escape." Compare Is 37:32; to the deliverance from Sennacherib there described Grotius thinks Obadiah here refers. "Jerusalem shall not be taken, and many of the neighboring peoples also shall find deliverance there." Unlike Judah's heathen foes of whom no remnant shall escape (Ob 9, 16), a remnant of Jews shall escape when the rest of the nation has perished, and shall regain their ancient "possessions."

there shall be holiness--that is, Zion shall be sacrosanct or inviolable: no more violated by foreign invaders (Is 42:1; Joe 3:17).