Support for 3.6.9 had already ended actually, the servers are only still running because 3.6.10 hasn't gone final yet (I planned on taking them off-line earlier this year originally). The 3.6.9 servers will go off-line when the new SquadWar support gets officially released, or Novemeber 1st of this year, whichever happens to come first.
When the updated version of the current website goes live (no ETA right now, as soon as I can do it though) it will have have a message on there for 3.6.9 server daemons that they are no longer supported and to move to the 3.6.10 daemons instead. And once the new server/website code (that goes with FSO 3.6.10 final) goes live then I'm probably going to post a sticky in the forums about the 3.6.9 servers going off-line in a few months as well.