It may be the Lord … will hear; i.e. "will notice," or "will punish." If Isaiah laid the matter before God, and prayed earnestly, it was possible that God would intervene to save Judah, and punish the blapshemous words uttered.
The living God. In opposition to the dead idols of the heathen, which had neither life, nor breath, nor perception (see Psalms 115:4-8; Psalms 135:15-18). The remnant that is left. It is usual to explain this of Judah generally, which still survived, although Israel had been carried away captive.
But perhaps the contrast is rather between the numerous Judaean captives who had been taken and conveyed to Assyria by Sennacherib when he took the "fenced cities" (Isaiah 36:1), and the portion of the nation which still remained in the land.
Sennacherib says, in his annals, that he took "forty-six" cities, and carried captive to Assyria above two hundred thousand persons.