Shrinking pool of dark fiber?

Well, the pool of dark fiber remains, but industry consolidation may eliminate competition among sources of dark fiber on specific US routes. 

I just caught up with the news Level 3 to acquire Looking Glass Networks. Last month's story was Qwest to acquire OnFiber.  Is this a trend?  And, if so, does it represent long overdue increases in efficiency, or worrisome monopolization of selected fiber routes?  Unfortunately I don't know anywhere that complete fiber route maps are available, so the answer may only emerge as individual companies endeavor to acquire dark fiber on specific routes.