That's exactly what LOTS of people have been saying for years. No existing tanker met all the requirements and meeting all the requirements required development. So the oft repeated mantra of "if only USAF had bought A330MRTTs they'd have had their tanker years earlier" is tosh. That is what I'm arguing against.
There's 'development', and then there's
development. No one can truly say what might have been, but given the nature and extent of the modifications that would have been needed to turn the MRTT into the KC-45A and given the track record of the MRTT since the KC-X contract was first awarded back in 2008 I don't think it is too much of a leap of fatih to suggest that the USAF would now have the fully operational tanker-transport it desperately needs had it stuck to its original decision.