The Unity team made a difficult decision to abandon Flash. As a result, the sale of licenses for this platform stops, support remains for 4.x.
The following reasons are named:
There is no certainty that Adobe will develop Flash. This is indicated by the cancellation of the development of Flash Player Next , the instability of the latest builds, the transfer of Adobe employees from Flash Player to other projects. *
The trust of both developers and the Unity team to Flash has been eroded due to the introduction, and after the cancellation of the income distribution model ( Stage3D + FastMemory ). From now on, the platform can no longer be considered reliable and constantly evolving.
Developers are gradually moving away from Flash, while Unity Web Player has experienced unprecedented growth in recent months.
* Apparently, there is a view of Thibault Imbert’s Flash Team Lead to develop the Web Platform.