I agree about them paying for it, and that discussion will be in the cards. My parents offered to pay for my college, but I ended up paying for about 75% of it through work and scholarships (taking 5 years instead of 4 as a coop student). I have no idea what road my kids will take, but unless they turn out to be total s&%!heads (joking, kids!) I'd like to be able to provide a similar option to them. But I also don't want to overinvest in a 529 and then have kids that get full rides, or decide to pay for it themselves or whatever.
It seems a risk of a 529 is much more than just what return it'll yield, since the amount you'll need could be anywhere from zero to med school.