Jesper,
as always: you've hit the nail right on its head! Replacement indeed means replacement of the module (if one is available) or replacement of the defective part on the module. Either way this will mean more or less considerable downtime.
I do know companies who are already busy changing over to S7. They however hold on to the S5 parts they take out, because of reducing downtime on machines which are scheduled to be refurnished with S7 on a later date.
I believe there will be opportunities ahead if you can get hold on some S5 modules to trade in the near future. Especially people who don't believe the downtime part could well be forced to pay high prices to those visionaries, simply because they have no alternatives.
Kind regards,