EA initially planned three times more DLC for Battlefield 3 than Bad Company 2, but it looks like they'll be reneging on that: developer DICE and its executive producer Patrick Bach says they're now planning "12-18 months" of value, though that could change.
"Right now, we haven’t planned [whether or not we'll do anything beyond the 18 months] out yet,” said Bach. “Depending on what happens, we’ll change things and add to it. We’re very keen on listening to the community and we read all the forums and posts, we make sure we implement any changes that need to be implemented and of course validate through data."
Whether the 12-18 month window goes from the October 2011 launch or not isn't clear, but either way, it looks like End Game could quite possibly be the last content pack, though it does still leave room for the possibility of more.
"Value" seems to indicate patching support as well, so there could be yet many more improvements to look forward to beyond the expected May or June patch.