Starting with Hazelcast Enterprise 3.8, each next minor version released will be compatible with the previous one. For example, it will be possible to perform a rolling upgrade on a cluster running Hazelcast Enterprise 3.8 to Hazelcast Enterprise 3.9 whenever that is released.
Is there any plan to support rolling upgrades between non-subsequent minor versions in future?
For e.g. from 3.8 to 3.11 ?
Unfortunately no. Rolling Upgrades can and will only be used with subsequent versions.