The day Canon adds articulating screens to their xD line of products is the day I jump ship.
I think I understand where you're coming from: when ultimate durability is a top priority, adding another point of potential weakness could be a big step back. I'd be willing to bet, though, that the day Canon adds articulating screens to the 1D line, it's because they're robust enough to handle professional use in the field. Whether Canon ever goes that route is anybody's guess, but for now, the articulating screen doesn't look like it will make its way into a pro body anytime soon -- perhaps for the durability reasons you state. I wouldn't be surprised, however, if it makes it into the 6D. Technically, it's an xD body, but I don't think it's what Canon considers a pro body.
Just as a data point (or two, or three), I've had an articulating screen on three Canon (consumer) cameras: A80, G12 and 70D. The first two have seen plenty of abuse (each has an inverted corner from hard falls onto concrete). The screens both feel and perform as they did when new (this surprised me, actually). My kids have inherited the now archaic A80, and I use the still very relevant G12 for rugged outdoor stuff when weight/space is a concern.
The 70D is still like a new pair of shoes, wiping off every little smudge. The screen feels just as strong as the G12 (maybe a little stiffer). I'm confident that it will prove just as durable, but I can't help but knock on wood when I say that! Hence, I understand the concern a professional might have.
One other quick note: I managed to get my G12 covered in snow and very wet while snowboarding with my kiddos last week. There was water in and around the screen, buttons, lens assembly, et cetera. It was wet. I wiped it off, blew in some crevices, and all was fine. Obviously, snapshots of the family aren't critical to a professional shoot, but I was impressed with what that little camera can withstand...