With Coinbase's attitude, they're gonna get replaced by another exchange that understands Bitcoin is just as alternative a currency as any other altcoin, as the dominant currencies are FIAT(USD, EURO, etc).
Let's face the reality. Most "good" altcoin devs want to have a place in history, they want to make money, and they want to leave an impact on the world, and they can't do that through sidechains. Not to mention the huge economy based on other cryptocurrencie besides bitcoin, quite similar to stocks. Do you actually believe that they would give up on profitable trading for the sake of Bitcoin development? I think not. Bitcoin has flaws, and some people are out there to improve upon them down to the protocol level(Which is impossible to do with sidechains).
Good Luck Coinbase CEO, with that attitude I'm positive your exchange will not be the dominant one in the future.
If only for the sake of them wanting to have a place in history, and trying to do so by reinventing Satoshi's wheel, then I am going to have to go with Bitcoin and Sidechains.
Satoshi was smart enough to not let people know who he was so that everyone can remember than Bitcoin was not just about him being rich and famous (I'm pretty sure he's rich, and will be famous when he comes out after Bitcoin possibly becoming the status quo - at least he still had the patience to wait and test the waters).
Furthermore, making a Sidechain that solves or adds value is another way to have a place in history. To argue otherwise would be like saying all of IBMs achievements belong to Alan Turing. Yeah, IBM owes its success to the giants that shouldered them, but let's not be naive.
I am not for or against alt coins, but I am for utilizing cooperation. I think sidechains could do this.
