Most usage for platinum goes for catalytic converters in cars, when the world economy starts going bad the demand for autos will fall, less usage for platinum. Golds industrial demand is only 10-15 %, for silver around 50 % but in both instances the demand is inelastic to price. Also the industrial demand for both g&s is spread out between different industries, electronics, healthcare, food, energy, so even if prices rise 200-300 % the industrial demand will still be there.
With platinum almost all industrial usage goes for one industry. Also platinum has an substitution which is palladium that trades almost 1000 $ lower. Platinum will probably rise but i think you will see larger gains in g & s because investment demand for starter has a larger base and the industrial demand is not cyclical or price sensitive as with platinum.
The only thing that would give a boost to platinum is the obvious possibility of shortages if Russia decides to stop exporting platinum if an all out war broke out or is South Africa nationalized its mines. But if an all out war broke auto sales would probably plummet as well. Btw the rise in platinum the past two days is because of this:
http://www.miningweekly.com/article/...ead-2012-02-16