I would think it would be more like the banks buy bitcoins and shelf them to take them out of circulation. And yes prices will appreciate greatly but each coin that hits the market they will eat up just like they did with gold.
Yes holding will prevent this but how many are buying bitcoin with the intention of remaining in it for decades? I have a feeling most are speculating on a fairly quick profit (a few years).
And yes, what you posed in your second paragraph appears to be wha tthey are doing.