That's why it's useless to use. If you already know that prediction is not accurate why would you use it, It will only give you disappointment when real PR update comes and it was less to your expectation.
Last month when I used this tool it predicted a PR 4 but now when I use it it says Insufficient backlinks but I must say My backlinks have increased twice in the last one month . not only my site suffers this my friends website also suffers this thing . His site was given an indication of PR 3 prediction but now its gone . SO I dont think it is useful untill Big G updates its PR
PR Prediction tools always base their results at the backlinks of your site. Google changes it's algorithm constantly and there's a possibility that how they calculate PR would also change....
Really? So, you rely on PR Prediction tools? Are you sure the algorithm of that PR tool predictor is same as the Google PR algorithm? What do you think? Will Google Update it's PR?
there is no tool to check your future google page rank but you can check your PR on different google data centers