Rebalance primary shards, 2022

I, too, would like my primary shards to be balanced across the cluster.

I often reduce the number of replicas on older indices to optimize disk space.
When the cluster is reasonably idle, shards will recover from just-maked-for-deletion copies.
But quite often this means hours of indices being relocated to nodes that just deleted them.

Search engine landed me here: rebalance-primary-shards/14470
Best explanation of problems is here: how-to-rebalance-primary-shards-on-elastic-cluster/176060/4

The requirement for rebalancing was also asked about in primary-shard-rebalancing/6173 and cluster-reroute-automatically-reroute-and-rebalance-all-primary-shards/161757

Is this the proper way to inject solutions into older topics?

Primary purpose of this topic was to link existing topics to the github issue - no solution yet:

If it is currently not possible to demote a primary into a replica, would it be possible to bring up the replacement replica before failing the primary? Would that avoid the degradation of redundancy? I mean that it would work like ES does index clone - hardlinking the segments intead of copying.