That's the fear expressed by Charles Sturt University adjunct Associate Professor Ian Gray and Dr Merrilyn Crichton in a report discussing social inclusion in NSW.

"In 2012, Infrastructure NSW stated that the XPT would have to be replaced and coaches should be considered," Professor Gray said.

"The NSW Transport Master Plan says that the trains can only be kept operating until next year, and it takes years to obtain replacements.

"They are definitely in doubt. In the absence of an announcement saying the state government will replace the trains, in some degree it's inevitable."

Professor Gray said coaches did not have the amenities of the XPTs and those who were aged, or had health problems or disabilities, relied on trains.

"A lot of people find it difficult getting in and out of coaches and the other thing is access to toilet facilities and food," he said.

"Some people may stop travelling altogether when train services cease. Research has shown that social isolation can be exacerbated by available transport options."

Coaches started replacing trains in the 1970s and by 2004 trains served less than half the number of communities served by coaches.

Professor Gray said a deterioration in service levels could be blamed for a reduction in the number of passengers using regional trains in the past 20 years.

"The XPT train timetables have suited the needs of the trains more than the needs of the people and Dubbo is an illustration of this - people would like a train service to Sydney in the morning that gets back in the evening," he said.

"If we're making it more difficult as people age to travel to see relatives or do business, it's less attractive to live in the regions."

Orange Rail Action Group member Dr Peter Bilenkij said trains were preferred over coaches.

"They are much more comfortable and you can walk around," he said.

"There has to be a policy direction to concentrate on improving services in rural areas - we're working on getting a coach connection to the Bathurst Bullet and the fact that we haven't achieved that after one year of trying, that shows the level of interest in Macquarie Street in rural transport."