I don't believe we'll be able to keep addressing the trends by tweaking
current networks and increasing capacity. Whatever the network size,
whatever the underlying protocols there will be users with increasing
needs, and network admins struggling to meet those, while reducing
complexity and saving costs.

We'll keep increasing links capacity but not everywhere at the same speed.
We'll move to 40GE and 100GE in the DC while typical branch site will
probably only have few Mbps while all applications (and probably the
entire OS) will move most of the time in the cloud. Having a big network
has never solved netadmins problems. I remember some time ago when I was
operation manager of a large backbone my team had to troubleshoot
performance problems while my network was largely overprovisioned. We knew
problem was elsewhere but we had not only to justify the network was
meeting SLA's but also had to fingerpoint what was broken. Networks now
have to work closer to the application. And not just to provide typical
network metrics. I believe progresses Cisco is making on AVC (DPI,
performance metrics, application and routing optimization...) are addressing
exactly that.

Same for security, adding bigger firewalls won't scale. Companies can
hardly manage their firewalls and security appliances today and I don't
believe that current overlay solutions can survive when network boundaries
are becoming blurrier every day. New approaches should be used and
infrastructure must also do more than just transporting data while
expecting devices (firewalls, ...) to do the job.
For example, being able to transport the connection context across the
network through the use of Security Group Tags helps simplifying security
while reducing inherent complexity. I even believe we need to do more in
synchronizing security elements. Reputation built for email addresses and
web pages could certainly be better used by network devices.

Last, I believe none of the solutions I could think of will now be adopted
if not simple as network complexity is increasing. SDN and cloud solutions
will greatly help here adding orchestration capabilities. And not just
inside the datacenter.