Re: Plot ideas based on SPOILERS (general discussion)
The point is if Surtur is to be used, whether in this film or the next he will have been PRE-PLANNED and the EFX house(s) will have already been at work to bring him to the screen. They wouldn't just go "Oh you know what, we should use Surtur!" in the middle of the production and post process, whereby pushing back the film date.
Even if they were saving him for Thor 3, what is this comment about it delaying us getting the next sequel? TDW just wrapped up filming. There's still Avengers 2. We're not seeing Thor 3 for a good 3-4 years at the least. By the comments you posted in regards to almost a 2 year process rendering a character like the Hulk, that's MORE than enough time to get Surtur ready.