By Matt Hardy The Rugby Football Union have threatened Championship clubs with removal from the professional game structure if they do not agree to new terms relating to forthcoming seasons, Championship club Cornish Pirates have said. The South West club have written – in a statement they say is collective of all clubs – that two years of negotiations, some of which have excluded the second tier, have led to a proposition that could bankrupt Championship clubs and “further isolate the Premiership to the detriment of the game in England”. No team was promoted from the Championship to the Premi…