There have been rumors that some of the vessels are being readied for a major rebuild. This could involve pulling the superstructure off and replacing the entire engine with a smaller, more efficient one, or a major derating operation enabling the engines to run more efficiently at lower revolutions. Now, the engine is running at around 100 RPM and producing some 65.000 kW. If you could bring the engine speed down to 60 RPM, it would make for a top speed of around 22-25 knots and a much better fuel consumption. Such a rebuild is however highly unlikely as the engine has been designed from the get-go to be most efficient at about 100 RPM.
Another rumor says that the ships are going to be lengthened as has been seen with other container vessels with varying degrees of success! The problem here is that stuffing in extra sections makes for a less rigid ship more prone to stresses from bending and torsion. Many ships which have been elongated have had problems with cracked hull plates and water ingress. Other ships have broken in half (MSC Napoli anyone?). Furthermore, this would bring the ships into the post panamax category which would ake them even less useful to anyone!
I can't really tie this together with the ships being reflagged though! It will be very interesting to see what will happen in the future. It's not going to be in the immediate future though! These ladies will need at least one month reactivation notice before being ready! Right now, the engines are partly dismantled and oil and fluids have been drained off for the long term "storage".