You say you want the wall to open for flexibility... what kind of flexibility are you needing? How often are you going to need it. I mean REALLY need it? Once a month? 6 times a year? Twice a year? Once every couple of years?
This is the first question you need to ask yourself. I find that a lot of times we do things because we think we might need it, some day, maybe. And then we end up hamstringing ourself for the other 99-percent of the time.
A wall is a very useful tool--it holds shelves, pegboard, televisions, cabinets, etc., and it gives you a place to put work counters, tool cabinets, and stack equipment out of the way until you move it out into the main work area.
I find a big problem in my shop is not having enough wall space.
You could then put a single man-door in it, or even a double door, to move sheet goods, equipment, etc. We put a double-door in our walk-out basement, and it's an absolute life-saver. We use this door every month to load and unload all our equipment for our swap meet--tables, pop-up tents, boxes of supplies and parts to sell, PA equipment... I can't imagine doing that with a single man-door.
If it were me, I'd do a double door... I would NEVER do more than that, and I definitely wouldn't do the whole wall.
Look at Family Handyman, American Woodworker and other magazines you find at Home Depot--one of them puts out an annual "SHOPS" magazine, and they show guys doing great things in small spaces.
-Brad