I think that if Disney/Marvel hadn’t already released memos about BP, Guardians, and Spidey getting sequels, there would be a larger question mark over their fates. However, Spidey is filming its sequel now, and we know the other two will happen within the next few years. This is where Disney not releasing anything about Doctor Strange was smart. A little maddening (since there was a sequel tease), but smart.
Killing T’Challa and the Peters were shocking moments, but we know their sequels are coming, so the impact is dulled.