Tough, but not impossible.
Only one thing matters - show the airlines how much money they will make from Cardiff. Show them it is more than they can make from alternatives. Show them researched passenger and yield forecasts that are credible. That is all.
Once someone does that, the airlines will be beating at the door.
All else - like the road, the rail link - are just secondary and even tertiary issues.
The problem CWL has is that everyone wants to answer the easy questions....
TA