Delta's 737-900ER order

Yesterday came the news that Delta Air Lines will purchase 100 B737-900ER to begin the replacement cycle of it's narrowbody fleet. Until there is an official press release from the airline, it is rumours, but let us assume that the information is accurate.
Scott Hamilton is certain that Delta will have conversion rights to switch to the reengined version (the B737-9 as it stands now). If true, this little detail could hurt Boeing