I'm seeing the same thing, and I'm still in pre-nursing classes, too. My microbiology class started at 30 people; we are now down to 12 and probably less - today is the last day to withdraw without penalty. I've lost my entire lab group!
Honestly, I wouldn't let the high attrition rate frighten you. As with ANY program - nursing, law, English, hula, whatever - you're going to have certain groups of people. One group will be people who find their calling in another field while in nursing school - I actually had the reverse happen to me: I left my music conservatory to come do nursing! :chuckle There are the slackers who will wonder why their PS2 didn't help them pass pharmacology, or why all that beauty sleep during lab didn't make for an attractive grade. There are people who have misconceptions about what nursing really is - a foley catheter, a "whiff of diff", or a colostomy bag is going to freak the hell out of them, and they decide to pursue something else. There are people who have personal events get in the way, like a family member in the hospital or having to take a 2nd or 3rd job to support their family. There are people who run out of money. There are people who just simply decide they didn't really want to do it. There are people who win the lottery (oh, please let that be me...).
But for the most part, you don't have the entire nursing department chasing after you with a stick yelling, "Get out! Get out!"
I'm sure there will be difficult instructors, coworkers, fellow students, etc... and maybe I'm being an eternal optimist when I say this, but I remember something a professor told me: "You know, we WANT to see you succeed." Maybe other schools are more supportive than others - I don't know, I'm still pre-nursing. But in my musician days, in a school that was more cutthroat than a pirate ship, my professors were doing their best to help us all succeed.
Plus, if you really, really want to be a nurse, you will be. The path you take might look different than you imagined, or you might just sail on through. Either way, same end result. Just keep on keepin' on, and don't let statistics scare you!