This passage relates to the theme of resurrection and renewal.

Your passage is the very end of the book.  This is Sydney Carton’s final thoughts as he was about to die.  Although he does not actually say these things, they are suggestions to what he might have said.

If he had given any utterance to his, and they were prophetic, they would have been these… (Book 2, Chapter XV, p. 241)

Carton has made an interesting journey over the course of the book.  He was a drunkard, and though he was brilliant he was also pathetic.  He let Stryver take all of the credit for his work.  He let Darnay have Lucie. He hung around the Manette house almost like a stalker.  Yet love for Lucie changed him.  He became more self-confident, and more serious.

This speech does more than resurrect Carton as Darnay.  He gives Darnay a new life, making amends for the wrongs he has done and simultaneously freeing Darnay from his own past.  Yet he also renews the Manette family as a whole.  He saves them all.

Carton sees signs of renewal as he looks into the future.  He can imagine that the innocent will be redeemed, and the guilty punished.  France will survive.  In fact, it will be resurrected stronger and better, with its bloody past behind it.

Resurrection and renewal progress through the book in different forms.  We have the farcical, false resurrection of Jerry Cruncher, and the heartfelt resurrection of Jarvis Lorry and Sydney Carton.  Even Lucie grows stronger.  Everyone gets a new start, largely due to Sydney Carton.