IN DUE COURSE
Salary levels, taxes and cost of fuel, import taxes on buying foreign aircraft. Airbus use RR engines so no great change their. Boeing will be part of a deal with USofA so probably lower tax.
How the lease market works is another matter but I'm not sure this is actually modelled at the moment anyway.
Passenger levels might change, internally, holiday business travel as the UK economy reaches a stable level with regard to each country. At the moment the low pound is attracting a surge in tourism from a round the world.
The UK is not going to put up taxes to any country, leaving the Euro Tax Boundary 'should' make the UK more attractive to every country in the world, (that likes us).
The big question is UK<>EU taxes and passenger charges. I predict it won't change by more than 5% possibly with a bias in favour of Europe of a further 5% if the 'free market' area is too be readily available to British Made Goods.
Of bigger concern to the EU is the financial situation in Greece, Italy, Portugal etc whose banks are barely coping. They would devalue, but the EU rules don't allow that.
Of more interest for the future of UK air travel is which of the London Airports gets the Runway Expansion. I have opened a forum note on just that issue, hoping that we can do short game worlds to see how things work out as each airport gets the additional capacity.