A gantt chart is my biggest want right now. In my opinion, the current timeline view is completely insufficient for anything beyond a simple overview. Basic timelines have their place, but CPM scheduling, via a gantt chart visual, is the standard (and usually a client requirement) for most industries that manage sufficiently complicated projects.
Instead of modifying the timeline view, my vote would be to use the new Table 2.0 view (list grid prototype) as a foundation for an alternative scheduling view (as an optional collapsible right panel on the table view itself) that shows a more traditional Gantt structure
- Timeline Issue #1: Information isn’t consistently shown
An item’s information is restricted to only being on it’s timeline bar. This is difficult to read because first you have to hunt around the screen to find your entity, then discover that some of that information is very likely truncated because it is longer than the bar, which causes you to never be happy with the zoom level.
Timeline’s are fine for basic summaries. But visualizing the schedule of a complex project with lots of moving parts would benefit immensely with a familiar table layout to view/edit your information. Then the schedule bars can just show colors/shapes/symbols/etc.
- Timeline Issue #2: Information isn’t consistently structured
- The only hierarchical structure is through lanes. Without lanes, there is no way to create a consistent flow and visualize a critical path. Fibery sorts timeline items by slot availability, meaning regardless of user sorting rules if it can fit at the top it will.
- Lanes could maybe be usable, but there is a cap limiting only 100 lanes. Additionally, if you show lane fields to be able to edit in the timeline, lanes just take up too much space to see the big picture. Tables solve both of these problems.
As an example, Smartsheet.com already uses this exact type of collapsible right gantt view panel (as long as you have a date range). I think this is a very smart way of implementing it. You can close the gantt sidebar and focus on column editing or open it up to see the visual schedule representation.
I feel like dependency tracking wouldn’t be needed in the first release, but would be a huge upgrade and easily possible once the relationship properties feature is released, which would then allow dependency types: (start-to-start, finish-to-start, etc.)
Scheduling is critical in so many industries. And the possibility to house that schedule within Fibery allows enormous potential for customers to link their schedule with all of their other information 
Side note for anyone interested. This is a fascinating post from the Edward Tufte forum on scheduling graphics