If Harry Reid does indeed impose some sort of filibuster reform as part of the Senate’s rules at the beginning of the next Congress, he only needs 51 votes to uphold his decision (pending some unlikely adverse ruling by the parliamentarian or the success of some sort of Republican maneuver in the courts, which is even more unlikely). He may or may not (probably not) cut some deal with a few Senate Republicans to get them on board, but those wanting the most serious reforms possible would prefer the minimum in concessions to anyone.
So that’s why reform supporters should pay close attention to the names of Democratic Senators who have voted again filibuster reform in the recent past, as noted in this Alexander Bolton article in The Hill:
[Tom] Udall, Sen. Jeff Merkley (D-Ore.) and Sen. Tom Harkin (D-Iowa) proposed a package of reforms for the 112th Congress that would have eliminated filibusters on motions to proceed to new business. Their package also would have required senators wanting to hold up legislation or nominees to actually hold the floor and debate, and shortened to two hours the time that must elapse after a filibuster on a nominee has been cut off.
The package failed in a 44-51 vote, with Democratic Sens. Jim Webb (Va.), Max Baucus (Mont.), Herb Kohl (Wis.), Mark Pryor (Ark.), Jack Reed (R.I.) and Reid voting no. Democratic Sens. Dianne Feinstein (Calif.), John Kerry (Mass.) and Daniel Inouye (Hawaii) did not vote.
Webb and Kohl are gone, and Reid has obviously changed his mind; Pryor and Reed are obviously still around. DiFi has definitely made negative noises about filibuster reform, and even some who voted for it, such as Landrieu, Feingold, Rockefeller and Tester, have on occasions been shaky.
If this is a big deal to you, keeping the pressure up on Senate Democrats to discard the many rationalizations available for maintaining the old filibuster rules is the best place to start.