Pointless semantics, Riskman. The article says the three development aircraft are not under contract, and by definitition that means that they are not under contract "yet".
To my mind this is a no-brainer. More than £3 billion has now been spent on the MRA4 project, so it can't be cancelled, and there are three good airframes sitting there that could very sensibly be converted as R1 replacements, ensuring fleet commonality where possible.
The "let's buy the P-8" lobby are wrong on this one - it's a maritime patrol aircraft, and there's currently no funded programme to develop the 737 for SIGINT or any other special mission, so wait for it and lose another valuable capability.