One undeveloped feature of high speed rail is connectivity at the stations, especially for business travelers. I travel a lot on business, in the UK that usually means air, because I can drive to the airport, park up and walk to the terminal, board the plane and fly to my destination where my hire car will be waiting for me to drive to the company I am visiting, which may be around 50 miles from the airport. That connectivity is rarely available with rail, few if any stations have hire car facilities, car parking is limited and not very secure and it is still more expensive so my company will not sanction it.
Jim