How does this affect you fannishly?
There are many of us who have stories just perculating away, half-written (heck, I've even got one or two season 1 stories with Ford in 'em that remain undone). Season 4 has stripped away two key characters - Beckett and Weir. Will you continue to write in season 3 if you adored Beckett and/or Weir? Or will you 'go with the flow' and write season 4 fiction and just live with the loss? Will Sheppard/Weir fanfic will continue despite her loss (from the show) or will it wither? While stories which feature Ford are few and far between, Weir was an integral part of the show - heck, she was on SG1 before SGA even came about. It stands to reason that the feel of the show will change as well as Atlantis will now be under a military commander (Carter) instead of civilian (Weir). Or will it just be easier to have the team spend as much time off Atlantis as possible to avoid that?
And Beckett features so prominently in many stories (particularly those of a hurt/comfort (aka whump) persuasion) that how will fans add in Keller, who is the new kid on the block with basically no backstory with Sheppard's team??
Feel free to comment away. Myself, I haven't decided what to do, but have too many pre-season 4 stories to finish that I'm not altering them to fit season 4.