DT and SOA are two different monster. I personally wouldn't want to see them together. And not because of what DS and MP have said along the way, but because musically, they are a bit apart. I would rather see Haken or Fates Warning opening for DT, even Devin Tonwnsend.
Also, I'm afraid if this could ever happen, MP would turn it into a "let's play one song together because the fans would want it". Yes, fans would like it but I don't think DT would want it and it wouldn't be far for DT to be forced into that situation.