CoD Longevity

[SDDrew]

Hi everyone! Im a complete noob at COD as I havent bought the game yet. The one thing stopping me is I dont want to spend 50 bucks on a game that wont be supported for awhile. So can someone aswer these questions real quick. First off, Are the developers planning on releasing expansions with new theatres of war, or are they gonna just develope a whole new $50 game? Thats my biggest concern. Iv played IL2 1946 for awhile now and I want something a little more immersive, so this game looks perfect. Last worry I have is my computer is pretty weak at the moment, so do u think this will play at least on low settings? I play on a 720P T.V so I play on low resolutions.
CPU: AMD 955 3.2G
RAM:4G
GPU: 9800GT (weakest part!)