JIRA provides an excellent view of a roadmap, but in my view little or no support to aid the planning and maintenance of a roadmap.

To support some simple mechanism to enable the initial plans to be drawn up would significant aid my job, and also I believe be beneficial for many other users

I can describe the scheme that we use, and I hope the reviewer of this could determine if this is a suitably generic implementation to be used by other users, and therefore should be a feature of JIRA itself

The drivers that we have is that specific releases must support specific features that have been requested by customers, to support the specific features that they require in a build. Other thngs to consider are are build themes, and techinical or architectural issues that we have.

We have created some new bug types (Driver) and relationships (Requires, SupportedBy)

A Driver is some external pressure such as a agreed customer expectation, a internal business driver (e.g. development cost reduction, some theme) etc. A driver may have subtasks which are also drivers. Drivers are typically either some absolute binary measure, or a quantitive expectation. Drivers may have a required by date (typically if they represent or co-ordinate some external dependency)

A Requires relationship is used to map the features that contribute to a driver, but are not required by the driver.

A SupportedBy relationship is used map the driver to the are required by a driver

Requires and SupportedBy relationships are from a driver to a [driver, feature or enhancement]

When scoping a build we determine the features that we internally want to have in a build and also look at the drivers for that build. This is done by listing the drivers for a specific build target, and navigating all of the Requires relationships (for things that are not already in a previous build). If there is addition capacity in the build then the SupportedBy relationships are examined, and then other non associated work

This also gives us a crude way of managing impact.
If one of our drivers has a date changes (forwards or backwards) then the analysis can be revalidated, and the changes made on-mass if this is considered appropriate.

If a specific feature is delayed in the implementation we can view the impact of slipping the feature to a subsequent release