So, I've been hearing murmurs of this all day, and I'm not much closer to figuring out exactly what is going on here. However, I thought I'd bring you what I do know.
Essentially, before a big showdown shot between Hulk and Surtur in the Thor: Ragnarok footage shown last night at Marvel's panel, a throne room was shown in a sizzle reel where some godly like humanoids were seen. There have been reports that some think it is The Celestials, while some interpreted them as The Eternals. I've gone to our guys who were in the room, read tweets as well as reports from the night, and I can't seem to figure out the exact answer here. Some say it is Kirby-esque, others say the opposite.
I have heard that they looked normal sized though, so I would personally lean towards The Eternals. Remember, we have already seen the head of a Celestial in Guardians of the Galaxy in Knowhere, and that operated as a space station.
However, one thing is probably true, it seems that one of the groups will appear in the film, and I can't wait to find out which and what is going on with the higher powers at work in the MCU.