Backstory: Recently we've had problems aligning our different teams, marketing, ops and product with overall company goals. Each team has a slightly different approach to tracking key metrics. We've come together and ended up using google sheets as makeshift gantt chart. Each team has their own tab and we switch back and forth often at weekly team meetings.
The Idea: A team based gantt chart software platform.
Deep Dive: Similar to smartsheets you would build the ability for people to track tasks in a gantt chart. The key differentiator here is the ability to track dependencies cross charts/teams and overlay each chart, kind of like a heat map.
Once you gain adoption, you could build features like email alerts when a team moves a dependent task or comments/threads.
Validation: We would 100% sign up, I've tried to find a solution and haven't found one. This one is harder to build an MVP given you have to build a gantt chart piece of software before you build differentiating features.
Monetization: You should follow the freemium model, have a free option that is branded and gives people the option to share the charts and have a paid, premium monthly service.