Q:

Replacing the Picklist old values into new values? 

We have a requirement to updated the picklist values to new values.  We are doing it via "Replace". 
Whenever we do this, will the updated record fire Apex Triggers, Workflow Rules, etc.? 

A:

No, workflow rules, triggers, validation rules, flows, Process Builders, and any other logic that would run on a normal DML operation will not run as a result of using Replace.