I routinely code with 2-3 monitors, with terminals, IDEs, editors, debuggers, email, Skype, etc., in separate windows, so that I can quickly switch to the desired operation without opening and closing a lot of windows.
I sometimes use two monitors in portrait mode side-by-side for long code listings.
I think this and many other custom monitor setups, are more common than you think.
I see all kinds of custom KVM configurations around the offices and cubicles I work. Everyone's needs are different.
But back to your original question: if more people are using laptops, and less are using dedicated workstations with large (multi-)monitors, then that could just be a cost-cutting measure (paying for one laptop instead of a laptop + workstation), or maybe they are going to meetings after meetings too often to make a dedicated workstation even useful.
But it wouldn't be unreasonable to expect a docking station (or just the necessary cables), keyboard, mouse, and a large monitor, to supplement a laptop for long-term coding work.