Ask most Grand Theft Auto fans, and they will tell you that while GTA4 itself may have been a tad underwhelming after San Andreas (and especially in hindsight, considering it was followed up by the superlative Grand theft Auto V), its DLC was sublime. Two full length playable single player story expansions, The Lost and the Damned and The Ballad of Gay Tony, collectively referred to as Episodes From Liberty City, are arguably among the best GTA releases.
So it would be pretty nice to have them playable on our current generation machines, too. Happily enough, it looks like that may be happening- Episodes From Liberty City has been re-rated by the ESRB for the Xbox One (via NeoGAF), which suggests that it may be coming to Microsoft’s new console. Whether it will be via Xbox One Backward Compatibility, or via a full fledged re-release (in which case, one has to ask, why was the game not rated for PS4?) remains to be seen.
The original GTA4 and Episodes From Liberty City can, for now, be played on Xbox 360, PS3, and PC.