Last month, it was revealed that NXT Superstar Velveteen Dream was unable to compete due to an attack by The Undisputed Era backstage. While that was storyline based, we later learned that he may be suffering from legit back pain and Dave Meltzer has now claimed that he is indeed expected to be out fo action for at least a few months.
That means he won't be part of Survivor Series and probably won't be back in action until the end of 2019 or the beginning of 2020.
As for Elias, it's said that he's ready to return any day now. As you may recall, he suffered an ankle injury in September and while WWE had him record a promo taunting Shorty G (Chad Gable) back then, that was seemingly dropped because his recovery was taking longer than expected.
Now, though, it appears as if WWE is simply waiting until they have some creative plans for him before bring Elias back to television.