This is a very real possibility but my logic is that not everyone will up vote every 'Show HN' post, and assuming the number of 'Show' posts doesn't increase at a rapid rate, it should hopefully stay within reason. Of course, this might just be me looking at HN through rose tinted frames. The last thing I'd want is for the front page to become spam. My hope is to only get more people to support their fellow hackers, not to ruin the community.