Since United's the 800 lb gorilla at O'Hare, it's a little weird to think that they'd have a merger with anyone, let alone Continental. I've been reading the press releases and the pundit analysis about it, and I'm a little concerned.
Combined they go from 140 destinations out of O'Hare to 143 (adding Aruba, St. Thomas and San Juan, Puerto Rico.) Continental adds a lot of Mexico/Central American destinations, along with the South Pacific (fancy a trip to the Marshall Islands?)
On paper, this looks good. Customers win, the airlines win... so, who loses?
Well, anytime two companies combined there's an overlap of resources, so there will be job cuts. How many and where are anyone's guess. What will be interesting to see is how they handle the issue of seniority with the unions. How will it work when Continental pilots/flight attendants work with United ones? What does this mean for their competitors?
The good news is that they've got until the end of the year to shake things out. Naturally, expect the unions on all fronts to posture. Your Continental frequent flier miles won't go away, but will most likely be absorbed into the United Mileage Plus program. Until then, flying won't change until the end of the year.
So, if you fly United or Continental - you've got time and shouldn't worry. If you work for either of them, it might be a bumpy ride.