Middlecoin "can't" just switch to any coin at any time. This pool is pushing 9 GH/s now, how many pizzas is that anyway?
Even if the order books are there we still have the issue of "blowing up" some of the smaller faster coins and H20 is and has been aware of this for some time.
If the pool hash could somehow be load balanced

with dynamic quotas? so as to not overwhelm the smaller coins and allocate more hash as difficulty increases (if market demand allows), that could be a start.
Sure middlecoin could just switch to whatever network h2o feels like? As long as the buy orders are there on an exchange. Heck, let's just selfish-mine these coins with blatent 51% attacks! More profit, more BTC, less shitty alts.
Now if only middlecoin would offer auto-payouts in LTC - that's where the real potential lies for 2014.
This would not be within the best interest of us or h20. In fact, it isn't in our best interest to advertise middlecoin, although it is for h20, the guy with all the magic that we want to keep happy.
It's a balancing act, no doubt. And as long as it is profitable, more will come, until it is not.