Wirelessly posted (BlackBerry9630/4.7.1.40 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/105)

CO is still an earning and redemption partner with EK. The only thing that changed is the 3 flights between LHR and DXB that used to earn EQMs no longer do.

You will not be able to move your miles from OnePass to Mileage Plus so that option is out.

Are you planning on switching to the UA flight IAD-DXB or still flying on the EK nonstop? If the former you can still credit to CO and do OK or switch to UA if you think you will get 100K miles in a year. If you are going to stick with the EK flights it is a bit of a toss-up IMO. The EK program announced some significant changes recently that are going to make it much harder for low-revenue passengers to get much value. If you are flying paid biz/first it will probably pretty good for you.