If you look at Germany
In March 2014, transport minister Robert Goodwill MP discussed HS2 and GB domestic aviation routes, such as London to Leeds Bradford airport, with the House of Commons Environmental Audit Committee.
“If you look at a country like Germany you do not have these short domestic air routes because they have a high speed line between most of their major cities”, he said.
But it would seem that with a ‘high speed railway between most of their major cities’, Germany still has more busy domestic air routes than other EU countries, and more air passengers between Dusseldorf and Munich, than between Heathrow and Frankfurt.
There also seems to be more business travel between Munich and Hamburg by air, than between London and Leeds by rail.