Yeah. But I also said Add-On because I meant that they may just put Liberty City into the game, but make it so it's accessible by flight. Not changing the whole thing from San Andreas into Liberty City.
Also, I kept up with the Mods in Vice City and GTA 3. They also had a San Andreas mod for both games, well before San Andreas was even confirmed to be the next game, and well before people even thought about the next game. My favourite was the Real Mod for GTA 3. Replaced all of the stores to real-life stores, replaced the construction site in Staunton Island with the Mall that was pictured on the sign there, etc. It was great. Too bad I don't have a good enough Computer to handle it.