One of the headaches for ISVs and even internal developers was efficiently keeping tracking of the current API limits on the ORG. About a year ago Salesforce started to return these limits as part of the SOAP headers so that you could get a real-time count. The problem was that you had to burn API to get the latest count.
I'm excited to see in the pre-release notes for Winter '17 that Salesforce has simplified this. It used to be that for Enterprise Edition, Unlimited Edition, Performance Edition, and Professional Edition with API access enabled, the old calculation was based on your number of licenses and the license types, with a guaranteed minimum of 15,000 calls per 24-hour period. Salesforce has now changed this and set the minimum to 15,000 calls per 24-hour period.
To me this is a huge help - especially for smaller orgs that only have under 3-10 licenses. I'm very excited to get this rolled out and think it's a step in the right direction.