Did you read Cold Case, Molly/Carlos ain't happening. That ship was never launched, it never was to be. It exploded at the dock, never to be rebuilt. Carlos still has nightmares about that. Just look at his reaction in PT and BG to any mention of Molly. No amount of time is going to erase that trauma
Yes I did, several times in fact, thank you for asking. Since death is not final in Dresdenverse, nothing is final. There are three cheesy easy ways to bring them together. Next book will have different dimensions, maybe one has Carlos & Molly Ramirez spinning Cold Case as an improbable yarn to their dubious grandchildren. Towards the end of the series there will be time travel, maybe Harry goes back and Molly was never the Winter Lady. Maybe even SURPRISE, it was Nemesis all along. After all, he's already taken two other Fae Ladies. Pretty much any slipshod poser could write any of the above situations. I feel that JB is the caliber of author who can finesse Molly and Carlos into circumstances where they work out what happened, build trust, and have that type of relationship people dream of.