Assuming the wiki is right, the luxury tax threshold is $178 MM for 2013, and a first time exceedance is taxed at 22.5%. The Dodgers are at $235MM. We'll assume that is the right rough number - B-R had them at $195MM before Greinke, but there are additional costs beyond payroll in the tax calculation. The tax is a bit less than $13MM, effectively bringing their contract costs up to ~$248MM.
In other words, the Dodgers use all of their local TV revenue to cover payroll. If the Nats did that, they would have a <$30MM payroll.
Blue has pointed out that there are other penalties for having such a high payroll, including losing some general revenues of MLB and having to subsidize Loria et al. The Dodger should draw 3 million fans again, so maybe they can make money, but I think their payroll is unsustainable, especially when the luxury tax starts to escalate for repeat offenders. I'm expecting them to start dumping players like Ethier, and maybe look for a taker on Beckett and others if they somehow are not contending.