Very interesting problem to solve! Sharing some of my thoughts below based on your approach.
1) Unless the objective is totally not about making it a profitable vertical but only about data, you should look into the overall ticketing market attractiveness, e.g. size of market, growth rate, online penetration, current profitability and expected upside. This is to establish the base that ticketing is a good business to enter.
2) Customer: you should also look into what is the customer pain or passion point, what do they want more from the current ticketing market?
3) Competitors: beside those listed, are there also mobile ticketing platforms rising up? I am not familiar with the US market so pls ignore if it is already covered; in Asian market (China, SEA etc), there are a lot of rising startups providing ticketing services on mobile App.
4) You might want to think about the positive externalities on other business verticals of Google too.