Sounds like an opportunity for someone to buy yahoo messenger, make it work the way the oil industry wants it, and sell it to them as an industry specific chat service. No need to bring the rest of Yahoo along for the ride.
A buyer that tried to "sell it to them as an industry specific chat service" would destroy it in the process.
If something is absolutely critical to the running of your business, then at some point you need to at least consider paying for it.
I doubt they would pay $5 per user. or even a <your yearly salary> year flat fee.
and since they will not pay, you will have to run it on ads. And supporting online/mobile offerings (that do not have their requirement of local client/local logs) will always give you more money.
it is a lose/lose situation.
Isn't that the basis of enterprise linux?
Not to mention that any enterprise Linux user worth their salt has an expensive support contract with a major vendor (such as Red Hat). Either that, or they're confident that they have the in-house resources to support it. No enterprise user considers Linux to be "free as in beer", by any stretch of the imagination; rather, they're using it because it's the right tool for the job.
It would be a good way to teach an industry with plenty of money the virtue of paying for mission-critical services. Given that the industry runs on a service like Yahoo's, it's a pretty good bet that you could slip an innocuous looking change to the privacy policy past them.
FWIW, nat gas traders still use Aol Instant Messenger.