loose skin is a very individual thing depending on so many factors. Some people have a lot of it, others don't. It's hard to tell how yours is going to be. Like the above poster said, your age is a big advantage, but you're probably going to have at least some with a 100 lb loss.
For most of us, though, it's pretty easy to hide. I knew mine was there, of course, as did my husband and doctor, but no one else did. Most of mine was in my abdomen, so I just tucked the skin into my jeans or leggings and wore slightly oversized, longish tops to cover it up. Ta da! Gone. I did finally get sick of looking at it, though, and had it removed, but I highly doubt anyone who sees me can tell a difference. Naked - yes - but with clothes on - no.
I just want to add that a majority of pre-ops and early post-ops seem to be really obsessed with loose skin. I've worked with pre-op groups for the past two years and that question comes up EVERY TIME. I would also say that after losing all that weight, many of us (me too!) wonder why we wasted even one brain cell worrying about it. Losing a ton of the excess weight MAJORLY offsets the loose skin thing. I would take my loose skin any day over weighing 300+ lbs again. ANY DAY!!!!
btw - here is a picture of me BEFORE I had plastic surgery. I lost over 200 lbs. See all that loose skin? I don't, either...