Well, as we had experienced once when Google trivialized their backlink command, days aren't many before we see the end of TBPR. One may argue that TBPR is done with already anyway, until we see the end of that little greenbar, there will be many takers for it. The link development process will be the single most affected area with the absence TBPR.
"What if" Google were to pull down that greenbar from its toolbar?
1. The whole text link ad industry will come to almost a standstill.
2. Knowing if a site/page is indexed in Google will take a little longer.
3. Knowing the importance of an individual site/page will be more difficult if not impossible.
4. Knowing if a site is penalized will be difficult (Kind of a site that has hundreds of IBLs, but is a PR0)
In the absence of TBPR, how can one go about measuring the importance of a page? [Relevancy being a common denominator]
My list would include these, in order of importance -
a. Alexa Rank (With all its anomalies)
b. SERPs that the site/page enjoys for its target keyword/s.
c. Quality IBLs if any (such as dmoz)
I am sure there are many other metrics, but will be difficult to measure for each new potential link.
Now, please add, debate, ridicule... :)