No doubt they will stick together, however it appears that not in the case of "Alito"...
If an "extreme" nomminee comes before the senate (...and each of the 14 define extreme differently) then the gang of 14 will stop the nuclear option..
It appears that at least 2 of the GOP gang of 7 (remember it doesn't happen without 7 PUBBIES), have expressed the opinion that Judge Alito DOES NOT meet their definition of "extreme".. Which means that 2 OTHER PUBBIES would need to define Judge Alito as "extreme" at support the DIMS attempt to filibuster..... VERY UNLIKELY...
I agree with you on the question of a possible filibuster, but I still believe Collins, Snowe and Chafee will vote "no" in the up or down vote.