Hi Sara,
Thanks for the write-up. When our pricing change goes into effect, some of our customers will see a price decrease, some will see a nominal increase, and others will have a larger increase as you point out. You can see a full calculation of cost per users shared online: https://twitter.com/Pe_D/status/786313076027060224

In our online FAQ (https://bitbucket.org/product/pricing/upcoming), we tried to provide as much transparency into the change in price as possible. Below is an excerpt from our website. Also, as we mention there, we found that the majority of our paid customers were paying for seats that they were not using. Our new model ensures that customers will only pay for employees using Bitbucket.

Will I pay more under the new pricing model?

Yes. Some of you will see a price increase. Using the example above, you will pay $70/month under the Standard plan i.e. $20 more under the new pricing model. Additionally, the Standard plan will include 5 GB file storage for LFS and 500 build minutes for Pipelines per team.

- Raj Sarkar from the Bitbucket team