onycrowle -
Frankfurt - why would Lufthansa want to open a MME-FRA route when even Newcastle can't support a Frankfurt route and has to make do with just a route to Dusseldorf ?
Paris - Air France already operate a Paris route from Newcastle. AF are the same company as KLM. Given the large hub nature and closer proximity of Amsterdam to DTV rather than Paris (Amsterdam is almost 30% nearer) and the fact that Newcastle is not that far by land from Teesside, would a currently weak Air France / Cityjet *really* want to open a MME-PAR route and cannibalise an existing route ? Flybe also do a codeshare on the Newcastle-Paris route as well
London - given the train service from Darlington (every 30 mins, takes about 2h35) to King's Cross, the only London airport I can see working is Heathrow either by BA or with a BA flightcode. With no R3 in sight, BA can make far more cash by using slots to places like Chengdu than Teesside given they already fly to both Leeds and Newcastle.
The only passenger routes I think might work when there's an 800 lb gorilla up the A1, are point-to-point routes. That means either LCCs - perhaps Norwegian, suggesting to Wizz to give it another go or full scale grovelling to the golden harp - or going for holiday routes and charters. Alternatively, perhaps a cargo niche, or some other specialist aviation related activity.