As someone who went through Boosts 1.0 without applying a single boost, I will try to answer your questions.
No, the meta has no been destroyed. Users will boost the most powerful, meta relevant creatures as always. As the meta changes, they will boost them. Your unboosted or less boosted team will have to adapt and change. Your meta will change along with theirs.
You have to learn to play a different game. Use their boosts to your advantage. Go into battle knowing they will always be faster and stronger.
Your team will have to be different. You cannot fight fire with fire, fight fire with water. The variety will come on your end. Your stable of usable creatures will increase while theirs remains the same.
They did before boosts anyway, nothing changed there. Look at the top teams, they all pretty much had the same creatures on them.
You will ‘derank’ or be lower in trophies, no doubt about it. You cannot compete on an even playing field. Question is, how far you let yourself fall.
They do not need to be lower, just different. Thor to Thor, their boosted one will almost always win. So don’t fight Thor with Thor.