Ethan,
The SDN train has indeed left the station, but has it truly reached market acceptance? Has the SDN market crossed the chasm, even this year? If it's a single point or short timeframe, '14 may be the year we point back to as that year.

While your title poses the question of whether SDN will happen, other questions follow if you assume "yes". A couple that come to mind: Will SDN be so pervasive that it's not even a technology area, it's just the way things work? If SDN can truly impact many/all parts of networking, what impact does that have on the skill set required for the jobs of the future? Will network engineers still care about internals and protocols for vendor solutions, or will the work with SDN focus more on design, orchestration, and workflow, with more of a pluggable approach, ignoring the underlying protocols? And as you stated "what will you/we do to be a part of it?"

Thanks for the post - nicely done.