I just read about this addition to the AWS EC2 pricing model:
If your needs change, you simply exchange your Convertible Reserved Instances for other ones ... When you make the exchange, you must acquire new RIs that are of equal or greater value than those you started with; in some cases you’ll need to make a true-up payment in order to balance the books. The exchange process is based on the list value of each Convertible RI; this value is simply the sum of all payments you’ll make over the remaining term of the original RI.
If I'm understanding this correctly, this is good news for those who are interested in FileMaker Cloud's potential but are unable to commit at the moment due to lack of schedules or whatever. Now you can lock in the significant discount of 3 year reservations without locking yourself out of FM Cloud for 3 years.
Previously if you bought a 3 year reserved Windows instance for FileMaker Server and later wish to switch to a 3-year Linux instance for FileMaker Cloud, you would have to sell your remaining Windows reservation on the marketplace. That being said, a 3 year convertible RI only saves 39% over on demand vs a standard RI which saves 51%.