Juggernauts (and by this I simply mean a strong RT alliance; your definition, TruNinja, is not one I use nor have I heard) truly are dangerous and should be stopped immediately *only* if you are certain people, namely, Austria and Germany.
England and France benefit, and can form a sort of "reverse juggernaut" against Germany while RT take the south.
Italy can go either way, either fearing being trampled after Austria or getting in on Austria and hoping later on to break up the RT alliance.
That's my opinion on it.
However just because Russia and Turkey ally, as you rightly point out, doesn't mean Austria, Germany, or Italy are screwed, nor does it mean EF will happen.
If one of the two partners is shitty for some reason, either by playing badly or being too selfish to their partner, the alliance will collapse.
This is most often the case in one of two ways in my experience:
1) Russia eats up most of the growth and by mid-game Turkey is at about 2/3 Russia's strength - this leads to a schism either because an arrogant Russia decides to stab Russia or because a disgruntled Turkey decides to try to even out the bargain by force.
2) Russia is engaged on too many fronts at once (usually when England moves on StP or if he is bounced at Sweden) and begins to collapse - Turkey will usually abandon the alliance and attempt to recover Sev, Rum, both, or even more.
I'm not married to juggernauts but they do tend to be a solid alliance just because Austria truly is so shitty.
Unless Austria is a wily, creative player, there isn't much good reason for either R or T to ally with him, because uncreative and untrusting Austrias usually kill Turkey once Russia is weak because he is behind them, or, after splitting Turkey with Russia, feel threatened by him and attack. Or finally Austria is simply attack from the north or west, and is a useless partner, condemning his ally to stalemate in their war.
My $0.02