Don't jump to conclusion too fast.

Enable safethreading and you will likely go to 2 or 3 instances, due to the many small requests you have. You may even go to 1 or 2 instances when they have finished optimizing their scheduler. So who knows, you may even end up with a lower monthly bill!!

You can limit the amount of instances. If you set it to 1, your site will be slower, not completely down. Just like a normal hosting box.