There's really no point in having another full DVD unless they'll include pre-BWP songs. Is Roadrunner going to pretend that the Lamentations DVD doesn't exist?
I don't see why they couldn't put the whole London show and another show with a different setlist, focusing mostly on Pre-BWP material. They don't have to do a full tour, just maybe a few 'special' shows like the ones they did for Lamentations with the heavy set and softer set.
Or they could put out a DVD include some songs from this London show (mostly GR songs), and then have another show which will be the 'main show' of the DVD of a set that will focus on older material. But I don't see a reason why they can't make it a double disc DVD or something. In Flames, Dream Theater, Amon Amarth, Arch Enemy have all done this recently in putting out a double DVD, why not Opeth too?