Would a DTV-SEN route be aiming at people travelling to/from London or to/from Essex ?
If aimed at people travelling to/from London, how would you persuade customers that it can provide a better service than a train between King's Cross and Darlington, given the high speed and frequency of the train service ? Also need to think about the direct Eaglescliffe-King's Cross train service as well as a competitor
If aimed at people travelling to/from Essex, why would an airline set up DTV-SEN when a route like Edinburgh-Southend seems a safer option ?
Peel seem to have decided they don't want 150+ seat aircraft at DTV. Therefore any DTV-SEN route would likely have to be using something with no more than 70 or 100 seats. Fewer seats means you have to charge higher fares to cover the cost of operating the flight. How do you persuade enough high-spending customers to fly DTV-SEN instead of just low-spending students / backpackers ?
Not saying it can't work - just that there are a lot of questions about such a theoretical route which might need to be carefully answered before it comes to reality.