Before any companies can start thinking about paying it bitcoin the mentality would have to be the salary is x BTC per hour not x amount of dollars worth of BTC an hour - other wise there is no benefit.
Some companies pay part of the salary in BTC, but I think to pay all of the salary in BTC makes sense only if your employees are spread across the globe. I read in another thread BTC will overtake USD in about 7 years, so I think this mentality could change soon.