I could understand some of that as a rumour, but a few counter factors are that even now they're in the Superleague again this year, they still have very small crowds, and RL fans "Oop Norf" think travel along the M62 corridor to be very hard, let alone to the "treacherous Big Smoke" for away games. I doubt that they'll need a potential alternative ground.
Broncos are listing their fixtures as being at Trailfinders ground, selling tickets to the games that start this w/e. I doubt they'd move it at the eleventh hour. Their second home game clashes with our game on the 16th, and they're selling tickets for that too.
Basically, it *could* happen, but I very much doubt it.