The problem is that most things that are "unexpected" are unexpected because they're very, very unlikely to work. Everybody expects an attack on the final mountain, but still only a few can follow the favourites. Andy Schleck can drop Contador on Tourmalet on stage 17 even if Contador expects it, if he is stronger. Doing something unexpected like attacking on Tourmalet today would be quite unexpected, but even if Schleck much is stronger, Contador and his very strong team would most likely be able to real him in on the 130 K there is from the top of the Tourmalet to the finish line.
The "predictable" strategies are predictable by virtue of being the smart strategies. I'm not going to say that it's always stupid to do an unconventional strategy, but it very often is. Attack from very far out (being the most typical non-conventional strategy) generally only works if you're not considered a real threat in the GC and it helps a lot if your opponents team is weak. Neither of these circumstances apply.
ETA: You can also try to split the field, which potentially give a very large gap, but the problem is that it's just so bloody hard to split of a significant part of the field, with enough of the favourites that there aren't enough people wanting to work in the second group, but not including Contador. Generally happens with side-wind, but again forcing the pace with side-wind is hardly an unconventional tactic. Something also happened in 1996, but I don't recall the details.
All true. If Schleck has the legs to make a go of it on the Tourmalet, he could win the Tour in dramatic fashion. I would love it if, after the final TT, he wins the Tour by a handful of seconds left from a minute+ gained on the Tourmalet.
But unconventional efforts are not likely to catch Contador/Astana out. Then again, there was 2006, so... I dunno. Does Andy have the descending skills to maintain something like that? Are there enough peaks (only three) in stage 17 to keep the chasing teams at bay? Not if he's alone.
If Schleck wins the Tour, he will do it by attacking on the Col du Soulor with one or a couple of others.
There are a lot of very strong climbers in this race who have been holding back with their eyes on the Tourmalet. I think a lot of them will have a go on the Soulor (waiting till the Tourmalet is too late, Contador will be in complete control), and, if Schleck latches on to the right one(s), he can use them up one side, down the other, and then for as long as they can hold on on the Tourmalet. Guys like Basso, Van Den Broeck (less likely, given his high standing in the GC), Van Summeren, Rodriguez, Moreau, LuLu or Evans may gladly help Schleck to yellow if it nets them a win on the Tourmalet and a boost in the GC.
But my favorite for this is Gesink. If Rabo send him up the road on the Soulor (sound strategy to shred Astana before the Tourmalet), and Schleck jumps across to him, then, well, that's perfect. It neutralizes/benefits Menchov/Rabo and puts the onus to chase on Contador. It's a perfect fit for both Rabo and Schleck--let's hope it happens!
So: take advantage of others' attacks to kill Astana on the Soulor.
If Schleck is up the road from Contador at the bottom of the Tourmalet, he could win the whole thing. If nothing else, it would make for a damned fine stage!