Fuel railings between Townsville and Mt Isa ceased in 2017 when Aurizon lost its Glencore freight contract to a grossly under-resourced PN. The resulting debacle saw most freight, including all fuel move to road. Aurizon has since come to an agreement with Glencore to supplement PN's freight operations.
However by that time BP and Shell had signed long term trucking contracts - so for at least the next decade, the only likely way fuel will return to rail would be a rail operator purchasing the trucking companies involved. Clearly that isn't much of an option as Aurizon scrapped most of its remaining Mt Isa line fuel tankers last year.
Aurizon still hauls fuel on standard gauge in Western Australia.