Traffic is the key. The sites that will be worth money are the sites with monster traffic at the dotcom, or decent traffic at dotcom with high paying keywords. Like credit report or loan sites that get good traffic in dotcom, and are generic enough that you could syphon their traffic in .co without losing the name in UDRP.
As a whole, the extention will absolutely bury the little guys, who chase names around for a few years selling back and forth to themselves. All of the new extentions teach new lessons to those who waste time going there, and then you realize that another two years of your life have been flushed down the toilet.
Sooner or later a new extention might work out, but they are designed to relieve speculators of their time and money.....nothing else. The only way to get true value in an extention is to have wide adoption by serious end-users. There is no other way to create long-term value. By definition, if speculators have all of the good names, then the party is over before it even starts.......you will NEVER get the traction needed for the extention to matter.