The fact that they have consistently stated that the sCO mainline fleet would be getting E+ this year, including the fact that it was stated again in the quarterly earnings call just a couple of days ago. And the fact that the company aggressively completed the retrofit of the 752 fleet to E+ before the end of January, is now approaching completion of the 738 fleet, has made significant progress with the 739 and 764 fleets… need I go on? All evidence points toward this project getting done, as they've stated it would. The only aircraft that aren't on the timeline are the 735 and 762 fleets, and those aircraft are being retired.

That's because none of the 753s have had the changes made yet. They're coming. They aren't done yet. Until that happens, the only E+ seating on the 753s will be in the exit and bulkhead rows. That doesn't mean that's the long-term plan for those aircraft; it just means they haven't started changing the seat layout on those planes (which has already been stated multiple times).