Repeat after me everyone: "Everything is going to be fine."
Everyone is freaking out about the move to 1.8, and already people are proclaiming the end of MCSG. We're still growing in terms of server population, and I doubt a change like this would change that.
I've been here since the 1.6 and 1.7 updates, and I've heard it all before. The reasons have changed, but the general tone never does. Anyone who knows the history of Minecraft updates knows that everyone hates everything about an update until they start to live with it, and then they can't imagine living without it. Give it a month. After that, the whole 1.8-only issue won't even be a thought.
I will repeat something that someone else said today though: "If you truly are a good gamer, you'll adapt to the changes and still find a way to win." Gamers who play for fun don't mind the changes. Gamers who play to win will adapt and overcome. Gamers who can't help but whine are the ones who get left behind.
From a Development standpoint, remember that the move to 1.8 is generally good for future developments, because we aren't anchored by the aging 1.7 anymore either. 1.7 may run "better", but that's because it's been around for over a year and thus modders were able to come up with the best efficiencies; they will do the same with 1.8 soon enough. 1.8 brings in a bunch of back-end improvements that we can take advantage of, including an integrated Spectator function. And being able to code exclusively for one version of Minecraft should streamline Development work, since now you aren't coding for two versions and making them cooperate.
I hope no one is blaming Chad, Devin, or the Developers for this change, because to be honest, they're merely reacting to the changes that Mojang enforces upon us. I was talking with Rusty earlier, and he stated that 1.8 fixes a lot of screw-ups that they left in in 1.7 (in addition to making a few more, because Mojang aren't the greatest coders). We too would prefer a stable update schedule or a lot of smaller updates instead of the large overhauls like 1.8 is bringing us, and thus cut down on the amount of revision and adjustment needed to acclimate to the new version. But alas, Mojang makes its will known, and we must obey.