You won't be black listed from the US carriers. At EK we currently have tons of FO's and CA's leaving for DAL, UAL, AA, Virgin America and Jet Blue. I even heard of one EK FO who left to go fly E170's at a regional. That should speak volumes about the quality of life at EK.
If you do come to EK do it with the mindset that you will not see the left seat. For you to upgrade the fleet would basically have to double. There is some attrition but it's not enough to get you in the left seat in a reasonable amount of time. Despite the fact that we currently have hundreds, probably thousands of FO's who meet the upgrade requirements Emirates just started advertising for DEC's again. Why? Because they can. It's cheaper to hire a direct entry CA than to train an FO then find, hire, and train his/her replacement. Read this paragraph multiple times before accepting a job offer. I'm guessing someone hired today would upgrade in about 10 years+.
If you do come despite the above paragraph make sure you don't accept a position on the 330. You will be an FO until they park the fleet and then you will start over again on the 380. It takes 3,000 hours in type to qualify for command. So if you spend 2-3 years on the 330 you are looking at another 4-5 years before you even meet the minimums to upgrade on the 380. But you will have hundreds ahead of you for upgrade. All the local cadets will be nearing upgrade by that time and they will go ahead of you as well.
Flying a 777/380 is nice but you won't be getting the 18-20 days off per month that a DAL/UAL/AA widebody CA gets. Instead you will have a mix of ultra short haul and ultra long haul, mostly on the backside of the clock, and about 8-13 days off per month on the Boeing. A typical 777 turn around flight leaves between 12am-3am and returns to Dubai from 7am-1300. Two pilots and 8+ hours of flight time over multiple legs. Time spent in the bunk does not count towards monthly or yearly maximums. You get your $12usd per hour of flight pay while in the bunk but that's it. Doing that month in and month out takes a toll.
Someting else that will come as a surprise to NA pilots is the general anti american sentiment in the EK training department. You will be constantly proving yourself to the Aussie/British trainers who think you are non standard and a sh#t pilot. If you study hard you should be fine but it does wear you out over time. Heaven forbid you come off an RJ. My first three years every CA asked me if I flew an RJ prior to EK and when I said I came off a Boeing they then went on to talk about how many problems EK had with all those American RJ pilots they were forced to hire. That really shows how the training department feels about NA pilots in general. For some reason they think an ex BA guy who spent two years sleeping in the bunk is infinitely more qualified than someone who spent years flying multiple legs a day in the left seat of an RJ in all kinds of weather. It makes no sense to me but it's the reality of Emirates. During my training the only ex RJ pilot in our class was mercilessly hammered for little mistakes while the rest of us went through relatively unscathed.
I'm sure this all sounds like sour grapes and EK is not all bad. You will fly nice equipment to cool places. But you will work as hard as a Mesa pilot and you won't save nearly as much money as you expected. There are no labor laws and your contract will be changed/broken with no recourse. We used to have 78 hour lines with overtime paid above 78. Now we fly between 91.5-92 hours per month for the same compensation. You are guaranteed 42 days of vacation per year but the company will only award 30 of them and the rest will be in an ever increasing leave bank that you can't use. No matter how productive you are you cannot be awarded more than 5 days off in a row. Staff travel is becoming more and more difficult so it's going to be very hard to get back home. The hard truth is that the best days of EK are in the rear view mirror. They put on a spectacular road show though and I see how someone could fall in love with the place after an hour or two with the recruitment team.
If you must come to the ME then choose EY. Upgrade, training, the pilot culture and virtually every other metric is vastly superior at the moment. Or if you choose EK then plan on applying to DAL the moment you get some time and be prepared to pay off your EK bond once you get the call to come back home.
Sorry to be the bearer of bad news. Best of luck to everyone.