The basic problem is Alex never had a business plan, which means Amazon never figured out how to build a profitable (sustainable) business. It also looks like Alexa's leadership gamed internal metrics to make Alexa look far more successful than it really was. I think this is what we can learn from Alexa:
1) Do not assume you can build a business, and then make it profitable. You always need to understand how a business can become profitable. Also, avoid fuzzy ideas, and metrics. For example, claiming unprofitable product X, is a success because it helps a company's brand, or causes people to buy more of product Y unless you have very very very strong evidence to back up these claims.
2) Dishonesty and bullshit do not work - Leaders, and teams need to be honest with themselves and with senior leadership. Do not use metrics to mislead other people, and point out flaws and limitations in metrics. Also, misleading people in general is not a good idea, and it harms organizations.
3) While killing products prematurely is a bad idea (see Google), continuing to support failing products for decades is probably not a good idea either.
I wish the Alexa team luck. I hope they can figure out how to create a profitable business which delights customers.