On a quick Analysis on the Pound/Dollar this morning, it is butting up against a long-term high resistance level at the moment, it has fallen away and re-tested it several times over the last several days and we have a fair amount of B-Divergence, I personally don't see it breaking through.. I looked back as far as 2012 briefly and we haven't seen this market reach these highs in a long time, but I do believe its running out of steam..
In terms of where it may go - well the first place one always looks is the next significant S/R level - so I would expect it to hit 1.70620's in the initial drop - then probably further down steps from there..
i find the classic RSI not to be so reliable to identify OB/OS consistently. hence the modified TDI on my chart showing we have not even entered OS yet.