Riverbed's announcement this week that it is shipping its PC client software has underlined the fact that PCs are now powerful enough to do the job of a WAN optimisation appliance.
That changes things - and it's going to change them even more.
Most importantly, it changes the value equation. In the past, WAN optimisation needed an appliance at each end because the storage and computation work involved was beyond the capability of an individual PC. Because it needed an appliance, it was only cost-effective when done for a number of PCs - a branch office, say - and because most of the applications in use were internal ones, that wasn't a problem.
Now though, any PC can do TCP optimisation, data compression, and some degree of CIFS caching, while Web 2.0 and SOA are breaking down the borders of application deployment.
The question then is what happens if a basic WAN optimisation client were included in the next version of Windows, for instance?
"I think Microsoft has already made moves in this direction," says Chris King, Blue Coat's director of strategic marketing. "It has improved the TCP stack in Vista with more flexible window sizing for example, and it has improved CIFS. It also hid the pain of MAPI so the user didn't see the slowness of downloading email.
"Now that Microsoft is improving TCP and CIFS, in a year or two there won't be any budget dollars in optimising those - although with TCP there will always be network issues outside the OS that you can work with, such as satellite latency.
"Plus, there will still be improvements you could do elsewhere, and a whole bunch of other apps will remain bulky on the wire, such as video and WebDAV, so over time we will shift onto other areas."
Could a new TCP be the answer?
One possibility would be for the WAN optimisation specialists to co-operate on extending TCP for the WAN, as it would enable them to move on from the basics that everyone needs to focus on the areas where they can really compete.
Most are wary of that idea, though. For example, Mark Lewis, Riverbed's European marketing director, argues that TCP does what it was designed for, and that most of the optimisation today is actually in other areas, especially in improving how applications communicate over the WAN.
"TCP was designed for the internet and it does a very good job," he says. "In fact the applications are the biggest contributors to network latency, and that's the responsibility of the application developers."