‘And he who sits on the throne said, “Behold I make all things new”.'
In case this all seems too good to be true God Himself now confirms it personally. Previously He has been passive while the action He has initiated goes on around Him. But now He speaks, for it is His own people who are involved, and He declares ‘Behold, I make all things new!' And then goes on to outline His intentions on the basis of the fact that He is the Alpha and the Omega, the Beginning and the Ending. Now He will prove Himself to be the Ending. he will bring His work to a satisfactory conclusion. (We can compare the similar situation in Revelation 11:3 when God said ‘I will give', in contrast with ‘it was given' in Revelation 7:2; Revelation 9:5).
Compare here Isaiah 43:18-19. God is doing a new thing and is providing life-giving waters, giving drink to His people, to His chosen (Isaiah 43:20, see Revelation 21:6 here), having Himself blotted out their transgressions and stopped remembering their sins (Isaiah 43:25). Compare also 2 Corinthians 5:17 where men in Christ form a new creation and all things become new. This is the final fulfilment of those first beginnings, brought about by the work of Him Who reconciled His people to Himself through Christ. The groaning of the old creation (Romans 8:18-25) has ceased and all is now fully restored.