You have to look at it from both sides though: If I started a business with Stripe as a processor, it's in Stripe's best interest for my business to grow as much as possible, because the higher my volume, the more they make. They'll want a good cut, but their goal is a long term relationship. It's not the same thing with Amazon: Every piece of intel I give them is an opportunity for them to eat my business.

I guess that if Amazon threw a crazy enough amount of money at them, then sure, everyone has a price, but how is joining Bezos' empire helping them? There's very little synergy in the other direction, so the premium for such an acquisition would have to be very large.

When you put the premium there, along with how being acquired by Amazon makes the competition more attractive, makes me think that something like that is unlikely.