This a tricky one.I don't know my first thought can be done in a workflow or not but it would be nice to use automation rules to help trigger something like this.
Create incident/ticket with 1 subtask. When subtask 1 is resolved it goes to an automation workflow that creates another subtask and on down the line. The problem with this of course is that you would need the ability to create subtasks from a workflow AND have a process that is standard and doesn't change such as installing a new network printer, etc.
You could do something similar to the above by creating incidents instead where thwy would link together and get created automatically through process automation but that's a different topic slightly.
Another possibility might be, again if possible, to have a process atuomation that checks to see if a subtask is resolved and if so, and there are more subtasks, to email the other assignees that one subtask has been completed. I'd have to look more into this one as it may be the easiest to implement (once I get rules working again on my test server!)