Let’s just say I update all my links with this new addition – and in a couple of days some of you discover that your PR has dropped because you lost a link from a site with high PR.
There is no negative in that. In fact it is a huge positive. Legitimate links now become even more legitimate, and exchanging links with unethical twerps becomes more undesirable and time wasting.
It’s a whole new ballgame of legitimacy that works several ways. Link exchanges could now focus only on their natural purpose, reccomendations to site visitors, if a site wants to do it that way. Which also means that links that don’t have the no follow tag now are more legitimate (which is a danger as mentioned above: spamming blogs that don’t use the tag becomes a bit more valuable).
The shakeup should be exchanging links will become a lot more genuine and difficult. You might not like that as a webmaster, but it will inevitably lead to you yourself making more thoughtful link exchange choices.