My Fowler is from the early 1980s and I can't find any reference to hopefully or sentence adverbs... :-(

I have a few guides to English usage (my favourite is Mind The Gaffe by the late Larry Trask). Each one of them has the infuriating habit of not containing at least some contentious point or other that I want to look up, and each one has its own hobby horses and various idiosyncrasies. My starting point is whether the expression in question is in common use and for how long it has been so, then the decision has to be made as to whether a degradation has taken place. The distinction between disinterested and uninterested is a valuable one and I'll fight to my last breath to keep it. I can't abide the (mainly American) habit of confusing alternate and alternative, and it will never be alright on the night... But English is not determined by professors or grammar police, and never has been.