I would like to see a quick follow-up from Years & Years and as people have already mentioned, London Grammar. Also, AlunaGeorge and Clean Bandit are due some new music I think, AG released a buzz single or new single in 2015 but no follow-up album or re-release materialised.
I'd also like to see some new music from Jhene Aiko, although she had a few more commercial song features last year that I liked, but not in the same way I like her previous dreamy chilled-out stuff, so I'm not sure. I get the sense that she's an artist on the cusp of either staying in the more indie R&B zone or making the crossover into mainstream hip-hop pop at the cost of making a completely different style of music.
Would be great to see Nelly Furtado and Pink making a comeback as some of you mentioned. I would expect Pink to release late in the year if she does at all, after the trap-EDM waves have passed, because her sound will probably be more of the same as she's done in her previous albums except slightly more modern.
I expect Gaga to release in summer or late in the year as well; off the back of American Horror story she has rationale for a new sound as well as people interested in her and where she's been.
One artist that I'm surprised no-one's clamouring about is Katy Perry. She's been very quiet since Dark Horse and I haven't really seen or heard her talked or wondered about either.