From the server side -- sure you can continue to patch/update your citrix apps etc.
If Google drops Chrome in 5 years time and in 5.5 years there is a massive flaw (some form of root-kit that saves every username/password and grants you access to the citrix system or the ceo's cloud based email account). If google decides that it wants to focus on Android and drops Chrome -- the pain could be immense. // This obviously doesn't apply for smaller faster moving companies.. But if you roll out 10,000+ Chrome systems -- Long Term Support plans are a good thing.
Otherwise - I agree. If you can replace a complex win/mac system with a cheap dumb chrome terminal -- the benefits for support are immense.
// Something like Ubuntu LTS might fit the bill perfectly so please don't think I'm just advocating Windows. I'm just considering that Google already produce a very successful light-weight linux-based OS (That has shipped far more units than Chrome likely will) and has a history of killing off products that don't get much traction (see Wave for a recent example)
Otherwise, I agree that the community aspect does differentiate it from past legacy products like Win2K.
The answer is an unqualified yes. According to Google, jailbreak mode is a feature of Chrome OS hardware. On the Cr-48, it requires flipping a small switch under the battery.
The hardware will be cheap, and the software will be ridiculously easy to maintain. It will be easy to adopt, and comparatively easy to abandon, if needed.