And this is what the majority of the population will want - they don't really care about the economic justifications for digital currency. All they want is to be protected from scammers, and to feel that their money is safe. And they trust the big banks for that, because by and large they've done a reasonable job of that. (Bitcoin has a far worse record on bank stability.)
You are right to point out that they don't want to buy up all the bitcoin but rather to co-opt this new source of interest for the common population. They like nothing better than a new carrot to dangle for which the masses will work their asses off, just to acquire some of it. T
Its the people who need to realize that the endgame with crypto-currencies isn't about buying some banker coin. Its about owning a method of transacting value which is running on a decentralized network like bitcoin.
So the banks will slowly strangle Bitcoin, while making use of the technology with their own coins. That's what they're already doing with Ripple, after all, where they're using the technology, but not the coins.
They may use ripple. The new investors may even profit from it. But when it comes to banks, they won't be sharing their profits with the common people. Ripple is going to be dead in the water and their isn't going to be any incentive for holding it.
And maybe that's no bad thing. If you truly believe in Bitcoin as an alternative currency, then the fiat link should be anathema to you. Once the speculators have been squeezed out it will revert to its original intention - as a peer to peer currency independent of the financial system. And your BTC will be worth just as much to you as they ever were.
That is my hope too. The people who want to trade or exchange services using crypto should be left alone. If more people want to adopt crypto for borderless transactions then it should be left at that. But its impractical for most governments as they will see it as a sort of attack on their hegemony or call it a parallel economy. Its a tough situation and they will probably tax the hell out of it. Despite that, I can see a future possibility when nations accepting of crypto --> deflationary reserve currencies --> Better Banking practices would adopt them and the regressive ones will alienate the segment of people who believe in it.