Seven angels, seven plagues, seven bowls. Lots to ponder here, especially since the plagues seem to be a bit of a "riff" on the Exodus and the plagues that are remembered each year at Passover.
I'm drawn back to the dream we find in the prophet Isaiah, however, particularly in chapter 56 where the holy mountain of Israel becomes a house of prayer for all peoples, and then in Isaiah 60:3 when "nations shall come to your light, and kings to the brightness of your dawn." That vision was rooted in a post-exilic mission statement, from the one the Biblical scholars call "Third Isaiah." First Isaiah announced the coming Babylonian exile, Second Isaiah spoke a word of comfort and encouragement to exiles heading home, and Third Isaiah articulates a vision of how this experience may have clarified the work ahead. It's also found in Psalm 86:9, and I am sure elsewhere as well.
It seems that John is remembering this promise, or glimpsing its fulfillment, from the Island of Patmos as we listen to the Song of the Lamb: "all nations will come and worship you, for your righteous acts have been revealed."
We also get the place name, Armageddon, in 16:16, which is worth noting. It seems to me that the plagues, and Armageddon, remind us that the work is hard, and the struggle is long. But the end of the work is the worship of the Lamb and all those witnesses from every tribe, language, people and nation. So we do not lose heart. We keep our eyes on the prize. As women and men, in spite of it all, we nevertheless persist.