Harry Reid (D-NEV) deiced not to seek reeleciton. This is not so shocking as once being the leader to become second fiddle in this non-functioning congress can be.... "unappealing".
from The New York Times
His departure at the end of 2016 will create an opening both at the top of the Senate Democratic hierarchy and in a Senate contest that would have been a megaspending slugfest in the presidential battleground of Nevada. Conservatives such as Charles G. and David H. Koch, the billionaire brothers who were a favorite target of Reid criticism in 2014, would have spared no expense in trying to oust him.
Senator Charles E. Schumer of New York, who helped Democrats capture the Senate in 2006 and has led their political messaging operation, is considered the favorite to succeed Mr. Reid as party leader. Senator Richard J. Durbin of Illinois, the Senate’s No. 2 Democrat, could also be a contender for the job, but it is unclear how strongly he would pursue it.
Now... who could replace him in Nevada where the Kock Brothers will sure to pour gazillions to take the seat?
In Nevada, Catherine Cortez Masto, the state’s former attorney general, is considered a strong Democratic candidate with Mr. Reid out; the Republican field will be fluid and is likely to include Michael Roberson, a State Senate leader.
from Salon we get a little bio
First elected to office in 1968 as a member of the Nevada Assembly, Reid served as lieutenant governor of Nevada from 1971 to 1974 and later led the Nevada Gaming Commission before winning a Las Vegas-based U.S. House seat in 1982. After two terms in the chamber, Reid was elected to the Senate, where he became minority leader in 2005, following the re-election defeat of former Democratic leader Tom Daschle of South Dakota. The Democrats’ recapture of the Senate in 2006 propelled Reid to the majority leader’s office, which he held until the Republicans retook control of the body last year.
I don't expect major fresh faces to become part of leadership, but this does leave a spot for Elizabeth Warren to gather momentum for a whip position and add a woman to the top 3 in the Senate.