This is just my simple draft of what i consider to be a natural and future-proof way of preparing for an eventual arranger, while still providing useful features in its early stage. Maybe it has already been suggested in this way?
Simple idea
A clip is a chunk of track data at any size. Every clip is defined one time in the pattern editor by marking its start and end with a new pattern effect letter (or via context menu). Every clip has to be named (defaults to “Clip #1” etc).
When a clip has been defined it can be either recalled or inserted.
- Recalled clips are write protected references to the original clip mark. (with fast gui access similar to todays automation markings)
- Inserted clips is just normal pattern data, originally inserted from a clip mark. This way they can be changed.
Recalled clips can be made “inserted” by a “make clip unique”/“insert this clip” menu.
Does this seem sensible and problem free enough? I think this is more simple and better than trying to do complicated stuff like previously suggested “meta-tracks”, or other exotic features steering renoise to a dead end.
Attached is just a simple screenshot of a context menu, to get the feel of it 
“Mark start of clip…” should automatically pop up a requester where you have to name your clip.