Allow Sitecore to be configured to use an out of process caching tool for it's internal caching (data caching, item caching, etc)
I would like to see the current internal caching mechanisms to be refactored to one that uses a "provider" based approach. This would allow Sitecore to be configured to cache some or all of it's data using Memcached, Redis, or a custom hybrid in-memory/out of process implementation.
In 8.2 the abstraction for the cache was introduced. Therefore, there is a possibility to implement own cache based on 3d party provider