Define "the extreme of either side". I would guess that registering as a Republican at some point in their life would define any nominee as being extremist. Certainly such extraordinary circumstances could justify a filibuster.
On the basis of what evidence are you making your statements?
So far as I can see, the "Agreement" has been faithfully followed by both sides, and I see no indication it won't continue to be followed, and passage of "super-extremists Brown, Pryor, and Owen" provide a benchmark for acceptable "ideology" so that issue has been taken off the table by their confirmation.
If they abuse the "extraordinary circumstances" line, the nuke will be supported by the 14. Again, all indications are that will come to pass if needed now.
With about 70% of Americans opposing a filibuster of judges, they'll bluster, but then pass President Bush's choice.