When will you implement my enhancement request?

Here is how I usually respond to this common question from my customers.

We cannot provide a definitive timeline for WHEN an enhancement request will enter development cycle, and here is why:

There is only one way for an enhancement to enter our development cycle. One of our Agile development scrum teams has to commit to deliver the requested change within a given X-sprint long release cycle. Before we even get to this point Product Management team considers overall release objectives and compiles a prioritized release backlog – a list of user stories ranked from 1 to N, where every work item is ranked relative to each other so that no two requirements have identical priority. Depending on the available development capacity (estimated ability of available resources to deal with uncertainty of research and development) the line is drawn somewhere in the backlog. The requirements below this line do not enter development cycle and are left for consideration in future releases.

Note how proposed enhancements may be evaluated multiple times, every time we start planning a new product release.

We utilize online Idea submission board. Having an enhancement captured as idea allows other customers add their votes over time. It could be that a new enhancement request upon initial evaluation is on par with hundreds of other similarly important and valuable improvement ideas. Over time with this approach we may find that when we plan our next release this idea is voted into top 10 most requested enhancements. That will have an impact on the odds of it entering the next development cycle.

How would you respond to such a question from your customer?