Okay, I think I figured out who the second artist is whose album has been postponed 'till next year. According to Rihanna's producer DJ Mustard, they're still in the early stages of her album, so apparently Rihanna may not be releasing this year after all:
http://atrl.net/forums/showthread.php?t=678246. Someone else did bring up an interesting point in that thread, though, that I never took into consideration. Beyoncé deliberately told her producers (specifically Ryan Tedder) to lie and make it sound like her album won't be coming out anytime soon before she dropped it out of nowhere. What if Adele is really planning a surprise release?

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I doubt it, though, and I hope she doesn't. Hopefully if Florence and Rihanna are both not releasing until next year, there's a good chance it was moved partially because of Adele. One Direction also moved their album release up, so... Adele may be releasing the single in October and album in November, which would be PERFECT.