As of 15 April 2015Predictions:Dark Blue - Democratic Hold
Light Blue - Democratic Pickup
Dark Red - Republican Hold
Light Red - Republican Pickup
Analysis:Assuming that 2016 will be as blue as 2014 was red due to changing demographics, the natural election cycle, and fractures in the GOP, it looks pretty good for the Democrats, who only need four or five pickups to regain control of the Senate.
Alabama - Richard Shelby is running for reelection... considering his relative popularity and the Republican-leaning tendencies of Alabama, this will be an easy hold for the GOP.
Alaska - I wouldn't be surprised if Murkowski (a moderate) is primaried by somebody in the Tea Party. Even if she isn't, the Democrats have a fair chance of winning this seat, assuming that 2016 is a blue year and Begich runs.
Arizona - Similarly, McCain could be primaried by a Tea Partier (Kelli Ward, Trent Franks, etc.), and even if he survives he could be ousted easily by a moderate Democrat like Kyrsten Sinema.
Arkansas - John Boozman is pretty safe for reelection. I doubt Pryor will seek another term, and he probably wouldn't win anyway. Of course, Beebe could easily win the seat if he wanted to, though I don't think he'll run.
California - Boxer is retiring, though California is so blue that her retirement is wholly irrelevant to which party will have control of this senate seat come 2016.
Colorado - Bennet faces low approval ratings in a state that just ousted its other Democratic senator, though I think he'll be able to hang on if 2016 is blue.
Connecticut - Easy win for Blumenthal.
Florida - Rubio can't run for both President and Senate, so he's out. Also, considering Rubio only won in 2010 due to the spoiler effect, this seat will be pretty easy for the Democrats to recapture with somebody like Murphy or Grayson...
Georgia - Georgia is becoming increasingly more centrist, though Isakson has incumbency advantage and high approval ratings, making this seat safe for the GOP.
Hawaii - Easy win for Schatz.
Idaho - Easy win for Crapo.
Illinois - Considering Kirk is in a blue state in what will probably be a blue year, he's an easy target for the Dems (Duckworth, etc.)
Indiana - This one was hard. Dan Coats is retiring, though Indiana is a red state so I could understand the argument that it will stay red come 2016. However, I think Bayh could win this seat back if he decided to run again (I'm assuming he will). If he doesn't, the seat is safe for the GOP.
Iowa - Grassley has the incumbency advantage and great approval ratings, making his seat an easy win for reelection.
Kansas - Easy for Moran.
Kentucky - I doubt Paul will win the Republican Presidential Primaries, though due to a new law being considered by the government of Kentucky, he may still be able to try to keep his senate seat. Assuming he is able to, this will be an easy win for the GOP.
Louisiana - Vitter is running for governor and will win easily, so the seat is wide open. Even though Louisiana is a red state, 2016 will be a blue year, so Mary Landrieu could opt in for a fourth term.
Maryland - Easy win for whoever wins the Democratic primaries to succeed Mikulski.
Missouri - This one was hard, but Jason Kander gets to beat Roy Blunt because I say so.
Nevada - I doubt Governor Sandoval will run, so this seat will be fairly Democratic (Masto, Titus, etc.) even though Reid is retiring.
New Hampshire - Hassan!
New York - Easy win for Schumer (future Majority Leader).
North Carolina - Same thing as with Missouri.
North Dakota - Easy win for Hoeven.
Ohio - Strickland!
Oklahoma - Easy win for Lankford.
Pennsylvania - Blue State + Blue Year = Blue Winner (bye Toomey)
South Carolina - Easy win for Scott.
South Dakota - Easy win for Thune.
Utah - Easy win for Lee.
Vermont - Easy win for Leahy.
Washington - Easy win for Murray.
Wisconsin - #feingold2016
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I got lazy towards the end.
Anyway, Final Results:
Democrats - 58 Seats; Republicans - 42 Seats