Well, we did get a great chance to vote our playlist for the Anniversary tour. It's the closest we will get to consumer demand. And a few underplayed gems (Midgard, Kali Yuga, Via Nocturna) did make it on the tour. Not to mention the whole Theli album, Adulurna and Summernight City. And hearing Via Nocturna with an orchestra live in Bucharest was sublime. But the fans couldn't keep their clicks off 'Rise of Sodom','Lemuria', 'Son of The Sun', 'Arrows from the Sun', or 'Ginnungagap', so all the other neat songs didn't get played.
A nice alternate playlist for me would include Eye of Shiva, Crowning of Atlantis, From the Dyonissian days, Nifelheim, Ljusalfheim, Helheim, SoTR, Emerald Crown, Up to Netzach/Floating back, The Dreams of Swedenborg, Abraxas, Wondrous World of Punt, Symphony of the Dead (instrumental) and for the encore covers Here comes the tears and Crying days ('you and meeee....'). That would be a whole different Therion. I think Crowning of Atlantis and A'arab zaraq are underrated albums, but I'm in the minority. And majority rules (when Chris wants it to).
But there might be a chance for these old songs to be played if Therion decide to make a Vovin or SotR anniversary tour (that would be sublime). Pink Floyd used to play whole albums from time to time, not just a few songs. Maiden did it too with the new album.