Re: Makes me glad I'm old, accomplished,
But "replica" is a copy. A slave is not a copy.
The issue appears to be that people are expressing butt-hurt and demanding change without thinking about what to change it to (that is clearly far too difficult). The existing terminology is clear and widely understood - A master is the primary control system that drives / feeds one or more slaves. Likewise, a slave is a system that is driven by another, if the master is down or non-existent, the slave won't do anything.
"master" / "replica" doesn't convey this style of relationship at all. It conveys the idea of there being a primary control system, with a copy of that system (so in the event the master goes down, the replica would take over and perform the role of the master).