Let's say a blog contains 10 backlinks from another site. Let's suppose that the linking is a reciprocal one(two way). Also let the blog has a PR of 2. Now If the blog owner (blogger) deletes all the link from his "blogroll" section, but his blog's link is still in the another sites (those 10 sites). Simply, what I'm trying to say is that the blog has switched from two-way linking to one-way linking (by deleting the links under his blogroll). Now my question is that "Would this result in an increase in PR, say 2 to 3 or 4) in a next PR update?"
Forget about pagerank entirely. Make linking decisions based on what benefits your end user. The time you spend agonizing over these kinds of useless metrics could be better spent improving your content, your business, locating relevant link partners, etc.