I was thinking the same. Some subjects like history, geography and science can sometimes be predictable. However, I don't think I'd ever chance predicting the maths paper.
I think you are just better off revising and practising, then doing a past paper, and try the predicted paper, because there's no harm in doing a practice paper, and if some similar questions do come up, you'll know how to do it.
I agree with ^ . Edexcel GCSE Maths tends to quite similar each year... There is nothing drastically different to the previous year. You'll all be fine! Good luck!
I have been using the predicted ones and learning the technique over the answers and then no matter what questions may come up i know fully how to tackle it. This method meant i got the silly 'Hannah has two sweets , prove n^2 -n-90=0' correct