A part of being a good guild is having a "plan B" in case the worst case scenario occurs. Clearly, you have no fallout plan for both tanks leaving. That is your own damn fault, not Blizzard's.
You guys just aren't prepared. Oh well, collective raiding break for a "few weeks" if you aren't willing to bring in a couple new members. That's the way it works. If a guild implodes because people quit, then your recruiting methods need a serious evaluation. Now is a good time to do that, before more of your members leave due to lack of leadership. Mediocre 10 man guilds are a dime a dozen, anyway.
There's just so much whining and crying these days, its ridiculous. Whatever happened to just doing what it takes to prevail?